STIHL MS 660 Magnum Chainsaw

Specifications

• Fuel tank capacity: N/A
• Chain oil tank capacity: N/A
• Weight (without bar and chain): N/A
• Engine power: N/A

Product Usage Instructions

Safety Precautions
Before using the STIHL MS 660 chain saw, it is important to read and understand the safety precautions to reduce the risk of personal injury. Some key safety precautions include:

• Only allow individuals who fully understand the manual to operate the chain saw.
• Read and follow the safety precautions and working techniques in the manual.
• Visit www.stihlusa.com for further information.
• If any instructions are not understood, contact a STIHL dealer or distributor.

Reactive Forces
When using the chain saw, it is important to be aware of reactive forces to prevent accidents. Reactive forces occur when the moving chain comes into contact with a solid object or when the wood closes in and pinches the chain. To avoid reactive forces:

• Hold the chain saw firmly with both hands.
• Be cautious of kickback, which can occur when the chain at the nose of the guide bar touches an object or when the wood closes in and pinches the chain.
• Do not cut with the tip of the guide bar.

Working Techniques
Proper working techniques are crucial for safe and efficient operation of the STIHL MS 660 chain saw. Some recommended working techniques include:

• Ensure a stable position and firm footing before starting the chain saw.
• Use the appropriate cutting techniques for different situations, such as felling trees, limbing, or bucking.
• Do not cut above shoulder height.

Cutting Attachment
The cutting attachment of the STIHL MS 660 chain saw includes the guide bar and chain. To install the cutting attachment:

1. Ensure the chain brake is engaged.
2. Remove the bar nut and cover.
3. Place the guide bar onto the bar bolts and align the hole in the guide bar with the tensioning hole in the saw body.
4. Install the chain around the guide bar, making sure the cutting edges of the teeth are facing in the direction of rotation.
5. Tighten the bar nut until it is finger tight.
6. Use the chain tensioning screw to adjust the tension of the chain.

Mounting the Bar and Chain
To mount the bar and chain on the STIHL MS 660 chain saw:

1. Ensure the chain brake is engaged.

2. Remove the bar nut and cover.

3. Place the guide bar onto the bar bolts and align the hole in the guide bar with the tensioning hole in the saw body.

4. Install the chain around the guide bar, making sure the cutting
   edges of the teeth are facing in the direction of rotation.

5. Tighten the bar nut until it is finger tight.

6. Use the chain tensioning screw to adjust the tension of the chain.

Tensioning the Chain

To tension the chain on the STIHL MS 660 chain saw:

1. Ensure the chain brake is engaged.
2. Loosen the bar nut slightly.
3. Turn the chain tensioning screw clockwise to increase tension or counterclockwise to decrease tension.
4. Check the tension of the chain by pulling it away from the guide bar. The chain should move freely but not sag from the bottom of the guide bar.
5. Tighten the bar nut securely.

Checking Chain Tension

To check the chain tension on the STIHL MS 660 chain saw:

1. Ensure the chain brake is engaged.
2. Hold the guide bar tip up and tighten the chain tensioning screw until the chain snaps into the guide bar groove.
3. Release the chain brake and let the chain hang freely.
4. Use a screwdriver to adjust the chain tensioning screw until there is no sag in the chain from the bottom of the guide bar.

Fuel
The STIHL MS 660 chain saw requires a fuel mixture of gasoline and engine oil. Follow these guidelines when fueling:

• Use a high-quality, unleaded gasoline with a minimum octane rating of 89.
• Use STIHL two-stroke engine oil or equivalent at a ratio of 50:1.
• Mix the fuel and oil in a clean, approved fuel container.
• Shake the fuel mixture thoroughly before each use.

Fueling
To fuel the STIHL MS 660 chain saw:

1. Ensure the engine is turned off and cool.
2. Remove the fuel cap from the fuel tank.
3. Pour the fuel mixture into the tank, taking care not to spill any.
4. Replace the fuel cap securely.

Chain Lubricant

The chain lubricant is necessary to reduce friction and prevent premature wear of the guide bar and chain. Follow these instructions for chain lubrication:

• Use STIHL chain lubricant or equivalent.
• Fill the chain oil tank with the recommended lubricant.
• Check the chain lubrication regularly during operation.

Filling Chain Oil Tank
To fill the chain oil tank on the STIHL MS 660 chain saw:

1. Ensure the engine is turned off and cool.
2. Remove the cap from the chain oil tank.
3. Pour the chain oil into the tank, taking care not to overfill.
4. Replace the cap securely.

Checking Chain Lubrication
To check the chain lubrication on the STIHL MS 660 chain saw:

1. Start the engine and let it idle.
2. Hold the guide bar tip near a light-colored background and rev the engine several times.
3. Observe if a thin line of oil is visible on the background.
4. If no oil is visible, stop the engine and check the chain lubrication system for any blockages.

Chain Brake

The chain brake is a safety feature that stops the chain from rotating in case of kickback or other emergencies. To engage or disengage the chain brake:

• To engage the chain brake, push the front hand guard forward until it clicks into place.
• To disengage the chain brake, pull the front hand guard towards the front handle.

Winter Operation

In cold weather conditions, it is necessary to adjust the STIHL MS 660 chain saw for winter operation. Follow these instructions:

• Preheat the intake air by covering the air filter with a winterization plate.
• Use winter-grade bar and chain oil for improved lubrication in cold temperatures.
• Consider using a fuel with a lower volatility to prevent starting problems.

Electric Handle Heating

The STIHL MS 660 chain saw features electric handle heating for improved comfort during cold weather operation. To activate the electric handle heating:

1. Ensure the engine is turned off.
2. Press the electric handle heating switch to the “On” position.
3. Wait for the handle to warm up before operating the chain saw.

Starting / Stopping the Engine

To start and stop the engine of the STIHL MS 660 chain saw:

1. Ensure the chain brake is engaged.
2. Place the chain saw on a flat surface.
3. Activate the decompression valve by pressing it down.
4. Pull the starter rope until you feel resistance, then pull it hard and fast to start the engine.
5. To stop the engine, release the throttle trigger and push the stop switch to the “Off” position.

Operating Instructions

For detailed operating instructions, refer to chapter “Operating Instructions” in the user manual.

Oil Quantity Control
The STIHL MS 660 chain saw is equipped with an Ematic system that controls the quantity of chain oil. This system reduces oil consumption and provides optimal lubrication. No additional oil quantity control is required.

Taking Care of the Guide Bar

To ensure the guide bar lasts longer and performs optimally, follow these care instructions:

• Keep the guide bar clean and free from debris.
• Regularly check the guide bar for wear or damage.
• Rotate the guide bar

STIHL MS 660

{
Instruction Manual Manual de instrucciones
WARNING This saw is capable of severe kickback which may cause serious or fatal injury. Only for users with extraordinary cutting needs and experience and training dealing with kickback. Chainsaws with significantly reduced kickback potential are available. STIHL recommends the use of STIHL reduced kickback bar and low kickback chain. ADVERTENCIA Esta sierra es capaz de causar contragolpes severos, los cuales pueden causar lesiones graves o mortales. Sólo es apta para usuarios con necesidades extraordinarias de corte y mucha experiencia y capacitación en el manejo de los contragolpes. Existen sierras con un potencial mucho menor de causar contragolpes. STIHL recomienda usar una barra y cadena de contragolpe reducido de STIHL.
Read and follow all safety precautions in Instruction Manual ­ improper use can cause serious or fatal injury. Lea y siga todas las precauciones de seguridad dadas en el manual de instrucciones ­ el uso incorrecto puede causar lesiones graves o mortales.

Instruction Manual 1 – 58
Manual de instrucciones 59 – 122

Contents

English

Original Instruction Manual

Printed on chlorine-free paper Printing inks contain vegetable oils, paper can be recycled.

Guide to Using this Manual

2

Safety Precautions

3

Reactive Forces

15

Working Techniques

20

Cutting Attachment

26

Mounting the Bar and Chain

27

Tensioning the Chain

28

Checking Chain Tension

28

Fuel

28

Fueling

29

Chain Lubricant

30

Filling Chain Oil Tank

30

Checking Chain Lubrication

31

Chain Brake

31

Winter Operation

32

Electric Handle Heating

33

Starting / Stopping the Engine

33

Operating Instructions

37

Oil Quantity Control

38

Taking Care of the Guide Bar

38

Air Filter System

39

Remove air filter

40

Cleaning the Air Filter

40

Engine Management

40

Adjusting the Carburetor

41

Spark Arresting Screen in Muffler 42

Spark Plug

43

Rewind Starter

44

Storing the Machine

44

Checking and Replacing the Chain

Sprocket

44

Maintaining and Sharpening the Saw Chain Maintenance and Care Main Parts Specifications Special Accessories Ordering Spare Parts Maintenance and Repairs Disposal STIHL Incorporated Federal Emission Control Warranty Statement Trademarks

Allow only persons who fully understand

45 this manual to operate your chain saw.

49 To receive maximum performance and

51 satisfaction from your STIHL chain saw,

53

it is important that you read, understand and follow the safety precautions and

54 the operating and maintenance

54 instructions in chapter “Safety

55 Precautions and Working Techniques”

55

before using your chain saw. For further information you can go to

www.stihlusa.com.

55 Contact your STIHL dealer or the STIHL

57

distributor for your area if you do not understand any of the instructions in this

manual.

WARNING
Because a chain saw is a high-speed wood-cutting tool, some special safety precautions must be observed as with any other power saw to reduce the risk of personal injury. Careless or improper use may cause serious or even fatal injury.

{
MS 660

This instruction manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process with electronic systems.
1

© ANDREAS STIHL AG & Co. KG, 2013 0458-178-8621-B. VA8.M13. 0000001844_009_GB

English
Guide to Using this Manual
This Instruction Manual refers to a STIHL chain saw, also called a machine in this Instruction Manual.
Pictograms
The meanings of the pictograms attached to or embossed on the machine are explained in this manual. Depending on the model concerned, the following pictograms may be on your machine.
Fuel tank; fuel mixture of gasoline and engine oil
Chain oil tank; chain oil
Engaging and disengaging the STIHL Quickstop chain brake Direction of chain rotation
Ematic; chain oil quantity control
Tension the chain
Intake air preheating for winter operation

Intake air for summer operation
Handle heating
Operate decompression valve
Operate manual fuel pump
Symbols in Text
Many operating and safety instructions are supported by illustrations. The individual steps or procedures described in the manual may be marked in different ways: N A bullet marks a step or procedure. A description of a step or procedure that refers directly to an illustration may contain item numbers that appear in the illustration. Example: N Loosen the screw (1). N Lever (2) … In addition to the operating instructions, this manual may contain paragraphs that require your special attention. Such paragraphs are marked with the symbols and signal words described below:

DANGER
Indicates an imminent risk of severe or fatal injury.
WARNING
Indicates a hazardous situation which, if not avoided, could result in severe or fatal injury.
NOTICE
Indicates a risk of property damage, including damage to the machine or its individual components.
Engineering Improvements
STIHL’s philosophy is to continually improve all of its products. As a result, engineering changes and improvements are made from time to time. Therefore, some changes, modifications and improvements may not be covered in this manual. If the operating characteristics or the appearance of your machine differs from those described in this manual, please contact your STIHL dealer or the STIHL distributor for your area for assistance.

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MS 660

Safety Precautions
Because a chain saw is a high-speed, fast-cutting power tool, special safety precautions must be observed to reduce the risk of personal injury.
It is important that you read, fully understand and observe the following safety precautions and warnings. Read the instruction manual and the safety instructions periodically. Careless or improper use may cause serious or fatal injury.
WARNING The use of this chain saw may be hazardous. The saw chain has many sharp cutters. if the cutters contact your flesh, they will cut you, even if the chain is not moving.
WARNING Reactive forces, including kickback, can be dangerous. Pay special attention to the section on reactive forces. Have your STIHL dealer show you how to operate your chain saw. All safety precautions that are generally observed when working with an axe or a hand saw also apply to the operation of chain
MS 660

saws. Observe all applicable federal, state and local safety regulations, standards and ordinances. When using a chain saw for logging purposes, for instance, refer to the OSHA regulations for “logging operations” at 29 Code of Federal Regulations 1910.266.
WARNING
Do not lend or rent your chain saw without the instruction manual. Be sure that anyone using it understands the information contained in this manual.
The use of noise emitting chain saws may be restricted to certain times by national, state or local regulations.
Use your chain saw only for cutting wooden objects.
WARNING
Do not use it for other purposes, since misuse may result in personal injury or property damage, including damage to the chain saw.
WARNING
Minors should never be allowed to use this chain saw. Bystanders, especially children, and animals should not be allowed in the area where it is in use.
Most of these safety precautions and warnings apply to the use of all STIHL chain saws. Different models may have different parts and controls. See the appropriate section of your instruction manual for a description of the controls and the function of the parts of your model.

English
WARNING Always stop the engine and activate the QuickStop Chainbrake before transporting or carrying out any work on the chain saw. This avoids the risk of the engine starting unintentionally. STIHL recommends the use of genuine STIHL replacement parts. They are specifically designed to match your model and meet your performance requirements. Safe use of a chain saw involves 1 the operator 2 the chain saw 3 the use of the chain saw.
THE OPERATOR
Physical Condition You must be in good physical condition and mental health and not under the influence of any substance (drugs, alcohol, etc.) which might impair vision, dexterity or judgment. Do not operate this chain saw when you are fatigued.
WARNING Be alert ­ if you get tired, take a break. Tiredness may result in loss of control. Working with any power tool can be strenuous. If you have any condition that might be aggravated by strenuous work, check with your doctor before operating this chain saw.
3

English
WARNING
Prolonged use of a chain saw (or other power tools) exposing the operator to vibrations may produce whitefinger disease (Raynaud’s phenomenon) or carpal tunnel syndrome.
These conditions reduce the hand’s ability to feel and regulate temperature, produce numbness and burning sensations and may cause nerve and circulation damage and tissue necrosis.
All factors which contribute to whitefinger disease are not known, but cold weather, smoking and diseases or physical conditions that affect blood vessels and blood transport, as well as high vibration levels and long periods of exposure to vibration are mentioned as factors in the development of whitefinger disease. In order to reduce the risk of whitefinger disease and carpal tunnel syndrome, please note the following:
­ Most STIHL chain saws are available with an anti-vibration (“AV”) system designed to reduce the transmission of vibrations created by the chain saw to the operator’s hands. An AV system is recommended for those persons using chain saws on a regular or sustained basis.
­ Wear gloves and keep your hands warm. Heated handles, which are available on some STIHL chain saws, are recommended for cold weather use.

­ Keep the AV system well maintained. A chain saw with loose components or with damaged or worn AV elements will tend to have higher vibration levels.
­ Keep the saw chain sharp and well maintained. A dull saw chain will increase cutting time, and pressing a dull saw chain through wood will increase the vibrations transmitted to your hands.
­ Maintain a firm grip at all times, but do not squeeze the handles with constant, excessive pressure. Take frequent breaks.
All the above-mentioned precautions do not guarantee that you will not sustain whitefinger disease or carpal tunnel syndrome. Therefore, continual and regular users should closely monitor the condition of their hands and fingers. If any of the above symptoms appear, seek medical advice immediately.
WARNING
The ignition system of the STIHL unit produces an electromagnetic field of a very low intensity. This field may interfere with some pacemakers. To reduce the risk of serious or fatal injury, persons with a pacemaker should consult their physician and the pacemaker manufacturer before operating this chain saw.
Proper Clothing
WARNING
To reduce the risk of injury, the operator should wear proper protective apparel.

Clothing must be sturdy and snug-fitting, but allow complete freedom of movement.To reduce the risk of cut injuries, wear the type of overalls, long pants or chaps that contain pads of cut-retardant material. Avoid loose- fitting jackets, scarfs, neckties, jewelry, flared or cuffed pants, unconfined long hair or anything that could become caught on branches, brush or the moving parts of the chain saw. Secure hair so it is above shoulder level..
Good footing is very important. Wear sturdy boots with nonslip soles. Steel- toed safety boots are recommended. Never wear sandals, flip-flops or go barefoot.
Always wear heavy-duty work gloves (e.g. made of leather or wear resistant material) when handling the chain saw and the cutting tool. Heavy-duty, nonslip gloves improve your grip and help to protect your hands.
To reduce the risk of injury to your eyes never operate your chain saw unless wearing goggles or properly fitted protective glasses with adequate top and side protection complying with ANSI Z 87.1 (or your applicable national standard).

4

MS 660

If there is a risk of injury to your face, STIHL recommends that you also wear a face shield or face screen over your goggles or protective glasses.
Wear an approved safety hard hat to reduce the risk of injury to your head. Chain saw noise may damage your hearing. Wear sound barriers (ear plugs or ear mufflers) to help protect your hearing. Continual and regular users should have their hearing checked regularly.
Be particularly alert and cautious when wearing hearing protection because your ability to hear warnings (shouts, alarms, etc.) is restricted.
THE CHAIN SAW
For illustrations and definitions of the chain saw parts see the chapter on “Main Parts.”
WARNING
Never modify this chain saw in any way. Only attachments supplied by STIHL or expressly approved by STIHL for use with the specific STIHL model are authorized. Although certain unauthorized attachments are useable with STIHL chain saws, their use may, in fact, be extremely dangerous.

WARNING
Never operate your chain saw if it is damaged, improperly adjusted or maintained, or not completely or securely assembled.
If this chain saw is subjected to unusually high loads for which it was not designed (e.g. heavy impact or a fall), always check that it is in good condition before continuing work. Check in particular that the fuel system is tight (no leaks) and that the controls and safety devices are working properly. Do not continue operating this chain saw if it is damaged. In case of doubt, have it checked by your STIHL servicing dealer.
THE USE OF THE CHAIN SAW
Transporting the Chain Saw
WARNING
Always stop the engine before putting the chain saw down. Carrying a chain saw with the engine running may be extremely dangerous.
Accidental acceleration of the engine can cause the saw chain to rotate. Always engage the chain brake when taking more than a few steps.

English
By hand: When transporting your chain saw by hand, the engine must be shut off and the chain saw must be in the proper position, i.e., grip the top handle and place the muffler away from the body; the chain guard (scabbard) should be over the saw chain and guide bar, which should point backwards, away from the direction in which you are walking. By vehicle: When transporting in a vehicle, keep saw chain and bar covered with the chain guard (scabbard). Properly secure your chain saw to prevent turnover, fuel spillage and damage to the chain saw. Fuel Your STIHL chain saw uses an oilgasoline mixture for fuel (see the chapter on “Fuel” of your instruction manual).

001BA258 KN

MS 660

5

English
WARNING
Gasoline is an extremely flammable fuel. If spilled and ignited by a spark or other ignition source, it can cause fire and serious burn injury or property damage. Use extreme caution when handling gasoline or fuel mix. Do not smoke or bring any fire or flame near the fuel or the chain saw. Note that combustible fuel vapor may escape from the fuel system.
Fueling Instructions
WARNING
Fuel your chain saw in well-ventilated areas, outdoors. Always shut off the engine and allow it to cool before refueling. Gasoline vapor pressure may build up inside the fuel tank depending on the fuel used, the weather conditions and the tank venting system.
In order to reduce the risk of burns and other personal injury from escaping gas vapor and fumes, remove the fuel filler cap on your chain saw carefully so as to allow any pressure build-up in the tank to release slowly. Never remove the fuel filler cap while the engine is running.
Select bare ground for fueling and move at least 10 feet (3 m) from the fueling spot before starting the engine. Wipe off any spilled fuel before starting your chain saw.

WARNING Check for fuel leakage while refueling and during operation. If fuel leakage is found, do not start or run the engine until the leak is fixed and any spilled fuel has been wiped away. Take care not to get fuel on your clothing. If this happens, change your clothing immediately.
Different models may be equipped with different fuel caps. Toolless cap with grip
WARNING In order to reduce the risk of fuel spillage and fire from an improperly tightened fuel cap, correctly position and tighten the fuel cap in the fuel tank opening.
To do this with this STIHL cap, raise the grip on the top of the cap until it is upright at a 90° angle. Insert the cap in the fuel tank with the positioning mark on the grip of the cap and the “open” mark on the fuel tank opening lining up. Using the grip, press the cap down firmly while turning it clockwise as far as it will go

001BA234 KN

(approx. 1/4 turn). The positioning mark on the cap should now line up with the “closed” mark on the tank.
Fold the grip flush with the top of the cap. Grip the cap and check for tightness. If the grip does not lie completely flush with the cap and the detent on the grip does not fit in the corresponding recess in the filler opening, or if the cap is loose in the filler opening, the cap is not properly seated and tightened and you must repeat the above steps.
Misaligned, damaged or broken cap
N If the cap does not drop fully into the opening when the positioning marks line up and/or if the cap does not tighten properly when twisted, the base of the cap may be prematurely rotated (in relation to the top) to the closed position. Such misalignment can result from handling, cleaning or an improper attempt at tightening.

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MS 660

1

001BA238 KN

Left: Right:

Bottom of cap in closed position ­ inner mark (1) in line with outer mark.
Bottom of cap in correct position for installation ­ inner mark is under the grip and not in line with the outer mark.

001BA239 KN

N To return the cap to the open position for installation, turn the cap (with the grip up) until it drops fully into the tank opening. Next, twist the cap counterclockwise as far as it will go (approx. 1/4 turn) ­ this will twist the base of the cap into the correct position for installation. Then, twist the cap clockwise, closing it normally.
N If your cap still does not tighten properly, it may be damaged or broken; immediately stop use of the unit and take it to your authorized STIHL dealer for repair.

See also the “Fueling” chapter in your Instruction Manual for additional information.
Before Operation
Take off the chain guard (scabbard) and inspect the chain saw for proper condition and operation. (See the maintenance chart near the end of the instruction manual.)
WARNING
Always check your chain saw for proper condition and operation before starting, particularly the throttle trigger, throttle trigger lockout, stop switch and cutting attachment. The throttle trigger must move freely and always spring back to the idle position. The Master Control Lever / stop switch must move easily to STOP, 0 or . Never attempt to modify the controls or safety devices.
WARNING
Check fuel system for leaks, especially the visible parts, e.g., filler cap, hose connections, manual fuel pump (only for chain saws equipped with a manual fuel pump). Do not start the engine if there are leaks or damage ­ risk of fire! Have the chain saw repaired by a STIHL servicing dealer before using it.
WARNING
Check that the spark plug boot is securely mounted on the spark plug ­ a loose boot may cause arcing that could ignite combustible fumes and cause a fire.

English
For proper assembly of the bar and saw chain follow the procedure described in the chapter “Mounting the Bar and Chain” of your instruction manual. STIHL Oilomatic saw chain, guide bar and sprocket must match each other in gauge and pitch. Before replacing any bar and chain, see the chapter entitled “Specifications” in the instruction manual and the chapter “Reactive Forces including Kickback”.
Since longer bars add weight and may be more difficult to control, select the shortest bar that will meet your cutting needs.
WARNING
Proper tension of the chain is extremely important. In order to avoid improper setting, the tensioning procedure must be followed as described in your manual. Always make sure the hexagonal nut(s) for the sprocket cover is (are) tightened securely after tensioning the saw chain in order to secure the bar. Never start the chain saw with the sprocket cover loose. Check chain tension once more after having tightened the nut(s) and thereafter at regular intervals (whenever the saw is shut off). If the saw chain becomes loose while cutting, shut off the engine and then tighten. Never try to adjust the saw chain while the engine is running!
WARNING
After adjusting a saw chain, start the chain saw, let the engine run for a while, then switch engine off and recheck saw chain tension. Proper saw chain tension is very important at all times.

MS 660

7

English
Keep the handles clean and dry at all times; it is particularly important to keep them free of moisture, pitch, oil, fuel mix, grease or resin in order for you to maintain a firm grip and properly control your chain saw .

engage that brake only for starting, because the saw chain may begin to rotate at high speed when the throttle trigger lockout is depressed (releasing the brake) in order to blip the throttle trigger after starting.

001BA113 KN 001BA114 KN

WARNING
Be sure that the guide bar and saw chain are clear of you and all other obstructions and objects, including the ground. If the upper quadrant of the tip of the bar touches any object, it may cause kickback to occur (see section on reactive forces). Never attempt to start the chain saw when the guide bar is in a cut or kerf.
For specific starting instructions, see the appropriate section of your instruction manual.
Starting
WARNING
To reduce the risk of fire and burn injuries, start the engine at least 10 feet (3 m) from the fueling spot, outdoors only.
Start and operate your chain saw without assistance. For specific starting instructions, see the appropriate section of the instruction manual. Proper starting methods reduce the risk of injury.
WARNING
To reduce the risk of injury from saw chain contact and / or reactive forces, the chain brake must be engaged when starting the chain saw. If your chain saw is equipped with the Quickstop Plus chain brake system, it is not sufficient to

WARNING Do not drop start. This method is very dangerous because you may lose control of the chain saw. There are two recommended methods for starting your chain saw.
With the first recommended method, the chain saw is started on the ground. Make sure the chain brake is engaged (see “Chain Brake” chapter in your instruction manual) and place the chain saw on firm ground or other solid surface in an open area. Maintain good balance and secure footing. Grip the front handlebar of the saw firmly with your left hand and press down. For saws with a rear handle level with the ground, put the toe of your right foot into the rear handle and press down. With your right hand pull out the starter grip slowly until you feel a definite resistance and then give it a brisk, strong pull.

The second recommended method for starting your chain saw allows you to start the saw without placing it on the ground. Make sure the chain brake is engaged, grip the front handle of the chain saw firmly with your left hand. Keep your arm on the front handle in a locked (straight) position. Hold the rear handle of the saw tightly between your legs just above the knees. Maintain good balance and secure footing. Pull the starting grip slowly with your right hand until you feel a definite resistance and then give it a brisk, strong pull.
WARNING
Be sure that the guide bar and saw chain are clear of you and all other obstructions and objects, including the ground. When the engine is started, the engine speed with the starting throttle lock engaged will be fast enough for the clutch to engage the sprocket and, if the chain brake is not activated, turn the saw chain. If the upper quadrant of the tip of the bar touches any object, it may cause kickback to occur (see section on reactive forces). To reduce this risk, always engage the chain brake before starting. Never attempt to start the chain saw when the guide bar is in a cut or kerf.

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MS 660

Once the engine has started, immediately blip the throttle trigger, which should release the Master Control lever to the run position and allow the engine to slow down to idle.
WARNING
When you pull the starter grip, do not wrap the starter rope around your hand. Do not let the grip snap back, but guide the starter rope to rewind it properly. Failure to follow this procedure may result in injury to your hand or fingers and may damage the starter mechanism.
Important Adjustments
WARNING
To reduce the risk of personal injury from loss of control and / or contact with the running cutting tool, do not use your chain saw with incorrect idle adjustment. At correct idle speed, the cutting tool should not move. For directions on how to adjust idle speed, see the appropriate section of your instruction manual.
If you cannot set the correct idle speed, have your STIHL dealer check your chain saw and make proper adjustments and repairs.
Holding and Controlling the Chain Saw
Always hold the chain saw firmly with both hands when the engine is running. Place your left hand on the front handle bar and your right hand on the rear handle and throttle trigger.

Left-handers should follow these instructions too. Wrap your fingers tightly around the handles, keeping the handles cradled between your thumb and forefinger. With your hands in this position, you can best oppose and absorb the push, pull and kickback forces of your saw without losing control (see section on reactive forces).
WARNING
To reduce the risk of serious or fatal injury to the operator or bystanders from loss of control, never use the chain saw with one hand. It is more difficult for you to control reactive forces and to prevent the bar and chain from skating or bouncing along the limb or log.
WARNING
To reduce the risk of cut injuries, keep hands and feet away from the cutting tool. Never touch a moving cutting tool with your hand or any other part of your body.

001BA087 LÄ

English
WARNING
Keep proper footing and balance at all times. Special care must be taken in slippery conditions (wet ground, snow) and in difficult, overgrown terrain. Be extremely cautious when working on slopes or uneven ground. Watch for hidden obstacles such as tree stumps, roots, rocks, holes and ditches to avoid stumbling. There is increased danger of slipping on freshly debarked logs. For better footing, clear away fallen branches, scrub and cuttings. Use extreme caution when cutting small-size brush, branches and saplings because slender material may catch the saw chain and be whipped toward you or pull you off balance.
WARNING
Take extreme care in wet and freezing weather (rain, snow, ice). Put off the work when the weather is windy, stormy or rainfall is heavy.

MS 660

9

English
WARNING To reduce the risk of injury from loss of control, never work on a ladder or any other insecure support. Never hold the machine above shoulder height. Do not overreach.
Position the chain saw in such a way that your body is clear of the cutting attachment whenever the engine is running. Stand to the left of cut while bucking.

001BA082 KN

001BA031 KN

Never put pressure on the chain saw when reaching the end of a cut. The pressure may cause the bar and rotating saw chain to pop out of the cut or kerf, go out of control and strike the operator or some other object. If the rotating saw chain strikes some other object, a reactive force may cause the moving saw chain to strike the operator.
STIHL recommends that first-time users should cut logs on a sawhorse ­ see “Cutting small logs.”
Working Conditions
Operate and start your chain saw only outdoors in a well-ventilated area. Operate it under good visibility and daylight conditions only. Work carefully.
WARNING
Your chain saw is a one-person machine. Do not allow other persons in the general work area, even when starting. Stop the engine immediately if you are approached.
WARNING
Even though bystanders should be kept away from the running chain saw, never work alone. Keep within calling distance of others in case help is needed.
WARNING
To reduce the risk of injury to bystanders and damage to property, never let your chain saw run unattended. When it is not in use (e. g. during a work break), shut it off and make sure that unauthorized persons do not use it.

WARNING
As soon as the engine is running, this product generates toxic exhaust fumes containing chemicals, such as unburned hydrocarbons (including benzene) and carbon monoxide, that are known to cause respiratory problems, cancer, birth defects, or other reproductive harm. Some of the gases (e. g. carbon monoxide) may be colorless and odorless. To reduce the risk of serious or fatal injury/illness from inhaling toxic fumes, never run the machine indoors or in poorly ventilated locations. If exhaust fumes become concentrated due to insufficient ventilation, clear obstructions from work area to permit proper ventilation before proceeding and/or take frequent breaks to allow fumes to dissipate before they become concentrated.
WARNING
Operate your chain saw so that it produces a minimum of noise and emissions ­ do not run engine unnecessarily and accelerate the engine only for cutting.

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MS 660

WARNING
Use of this chain saw (including sharpening the saw chain) can also generate dust, mist and fumes containing chemicals that are known to cause respiratory problems, cancer, birth defects, or other reproductive harm. If you are unfamiliar with the risks associated with the particular dust, mist or fume at issue, consult your employer, governmental agencies such as OSHA and NIOSH and other sources on hazardous materials. California and some other authorities, for instance, have published lists of substances known to cause cancer, reproductive toxicity, etc.
WARNING
Inhalation of certain dusts, especially organic dusts such as mold or pollen, can cause susceptible persons to have an allergic or asthmatic reaction. Substantial or repeated inhalation of dust and other airborne contaminants, in particular those with a smaller particle size, may cause respiratory or other illnesses. This includes wood dust, especially from hardwoods, but also from some softwoods such as Western Red Cedar. Control dust (such as saw dust), mists (such as oil mist from chain lubrication) and engine fumes at the source where possible. Use good work practices, such as always cutting with a properly sharpened saw chain (which produces wood chips rather than fine dust) and operating the unit so that the wind or operating process directs any dust raised by the chain saw away from the operator. Follow the recommendations of

EPA/OSHA/NIOSH and occupational and trade associations with respect to dust (“particulate matter”). When the inhalation of dust cannot be substantially controlled, i.e., kept at or near the ambient (background) level, the operator and any bystanders should wear a respirator approved by NIOSH / MSHA for the type of dust encountered.
WARNING
Breathing asbestos dust is dangerous and can cause severe or fatal injury, respiratory illness or cancer. The use and disposal of asbestos-containing products have been strictly regulated by OSHA and the Environmental Protection Agency. Do not use your chain saw to cut or disturb asbestos or asbestoscontaining products. If you have any reason to believe that you might be cutting asbestos, immediately stop cutting and contact your employer or a local OSHA representative.
Operating Instructions
WARNING
Do not operate your chain saw with the starting throttle lock engaged. Cutting with the starting throttle lock engaged does not permit the operator proper control of the chain saw or saw chain speed. Begin and continue cutting with the saw at full throttle, engage the bumper spike firmly in the wood (if possible) and then continue cutting. Always work with the bumper spike so that you have better control of the saw. If you work without the bumper spike the chain saw may pull you forwards suddenly.

English
WARNING
Never touch a saw chain with your hand or any part of your body when the engine is running, even when the chain is not rotating.
In the event of an emergency, switch off the engine immediately ­ move the Master Control Lever to STOP, 0 or .
WARNING
Always stop the engine before putting the chain saw down.
WARNING
The saw chain continues to move for a short period after the throttle trigger is released (flywheel effect).
Accelerating the engine while the saw chain is blocked increases the load and will cause the clutch to slip continuously. This may occur if the throttle is depressed for more than a few seconds when the saw chain is pinched in the cut or the chain brake is engaged. It can result in overheating and damage to important components (e. g. clutch, polymer housing components) ­ which can then increase the risk of injury, e. g., from the saw chain moving while the engine is idling.
WARNING
Your chain saw is equipped with a chain catcher. It is designed to reduce the risk of personal injury in the event of a thrown or broken saw chain. From time to time, the catcher may be damaged or

MS 660

11

English
removed. To reduce the risk of personal injury, do not operate a chain saw with a damaged or missing chain catcher.

and the like. Such objects may be flung off, damage the saw chain or cause the chain saw to kickback.

WARNING
Inspect antivibration elements periodically. Replace damaged, broken or excessively worn antivibration elements immediately, since they may result in loss of control of the saw. A “sponginess” in the feel of the saw, increased vibration or increased “bottoming” during normal operation may indicate damage, breakage or excessive wear. Antivibration elements should always be replaced in sets. If you have any questions as to whether the antivibration elements should be replaced, consult your STIHL servicing dealer.
If this chain saw is subjected to unusually high loads for which it was not designed (e. g. heavy impact or a fall), always check that it is in good condition before continuing work. Check in particular that the fuel system is tight (no leaks) and that the controls and safety devices are working properly. Do not continue operating this chain saw if it is damaged. In case of doubt, have it checked by your STIHL servicing dealer.
Your chain saw is not designed for prying or shoveling away limbs, roots or other objects. Such use could damage the cutting attachment or AV system.
WARNING
When sawing, make sure that the saw chain does not touch any foreign materials such as rocks, fences, nails

WARNING
If the rotating saw chain strikes a rock or other hard object, sparks may be created, which can ignite flammabale materials under certain circumstances. Flammable materials can include dry vegetation and brush, particularly when weather conditions are hot and dry. Do not use your chain saw around flammable materials or around dry vegetation or brush when there is a risk of fire or wildfire. Contact your local fire authorities or the U.S. Forestry Service if you have any question about whether vegetation and weather conditions are suitable for the use of a chain saw.
WARNING
Take special care when cutting shattered wood because of the risk of injury from slivers being caught and thrown in your direction.
WARNING
Never modify your muffler. Any modification could cause an increase in heat radiation, sparks or sound level, thereby increasing the risk of fire, burn injury or hearing loss. You may also permanently damage the engine. Have your muffler serviced and repaired by your STIHL servicing dealer only.
WARNING
The muffler and other parts of the engine (e.g. fins of the cylinder, spark plug) become hot during operation and remain

hot for a while after stopping the engine. To reduce risk of burns, do not touch the muffler and other parts while they are hot. Keep the area around the muffler clean. Remove excess lubricant and all debris such as pine needles, branches or leaves. Let the engine cool down sitting on concrete, metal, bare ground or solid wood (e.g. the trunk of a felled tree) away from any combustible substances.
WARNING
An improperly mounted or damaged cylinder housing or a damaged/deformed muffler shell may interfere with the cooling process of the muffler. To reduce the risk of fire or burn injury, do not continue work with a damaged or improperly mounted cylinder housing or a damaged/deformed muffler shell.
Your muffler is furnished with a spark arresting screen designed to reduce the risk of fire from the emission of hot particles. Never operate your unit with a missing or damaged spark arresting screen. If your gas/oil mix ratio is correct (i.e., not too rich), this screen will normally stay clean as a result of the heat from the muffler and need no service or maintenance. If you experience loss of performance and you suspect a clogged screen, have your muffler maintained by a STIHL servicing dealer. Some state or federal laws or regulations may require a properly maintained spark arrester for certain uses. See the “Maintenance, Repair and Storing” section of these Safety Precautions. Remember that the risk of a brush or forest fire is greater in hot or dry conditions.

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MS 660

WARNING
Some STIHL chain saws are equipped with a catalytic converter, which is designed to reduce the exhaust emissions of the engine by a chemical process in the muffler. Due to this process, the muffler does not cool down as rapidly as conventional mufflers when the engine returns to idle or is shut off. To reduce the risk of fire and burn injuries when using a catalytic converter, always set your chain saw down in the upright position and never locate it where the muffler is near dry brush, grass, wood chips or other combustible materials while it is still hot.

DANGER
Do not rely on the chain saw ‘s insulation against electric shock. To reduce the risk of electrocution, never operate this chain saw in the vicinity of any wires or cables (power, etc.) which may be carrying electric current.To reduce risk of electrocution, take extra precautions when cutting near power lines. Have the power switched off before starting cutting work in the immediate vicinity of power lines.
MAINTENANCE, REPAIR AND STORING
Maintenance, replacement, or repair of the emission control devices and systems may be performed by any nonroad engine repair establishment or individual. However, if you make a warranty claim for a component which has not been serviced or maintained properly or if nonapproved replacement parts were used, STIHL may deny coverage.
WARNING
Use only identical STIHL replacement parts for maintenance and repair. Use of non-STIHL parts may cause serious or fatal injury.

English
Strictly follow the maintenance and repair instructions in the appropriate section of your instruction manual. Please refer to the maintenance chart in this manual.
WARNING
Always stop the engine and make sure that the cutting tool is stopped before doing any maintenance or repair work or cleaning the power tool.
WARNING
Do not attempt any maintenance or repair work not described in your instruction manual. Have such work performed by your STIHL servicing dealer only. For example, if improper tools are used to remove the flywheel or if an improper tool is used to hold the flywheel in order to remove the clutch, structural damage to the flywheel could occur and could subsequently cause the flywheel to burst.
Wear gloves when handling or performing maintenance on saw chains.
WARNING
Use the specified spark plug and make sure it and the ignition lead are always clean and in good condition. Always press spark plug boot snugly onto spark plug terminal of the proper size. (Note: If terminal has detachable SAE adapter nut, it must be securely attached.) A loose connection between spark plug terminal and the ignition wire connector in the boot may create arcing that could ignite combustible fumes and cause a fire.

MS 660

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English
WARNING
Never test the ignition system with the spark plug boot removed from the spark plug or with a removed spark plug, since uncontained sparking may cause a fire.
WARNING
Do not operate your power tool if the muffler is damaged, missing or modified. An improperly maintained muffler will increase the risk of fire and hearing loss. Your muffler is equipped with a sparkarresting screen to reduce the risk of fire; never operate your power tool if the screen is missing, damaged or clogged. Remember that the risk of a brush or forest fire is greater in hot or dry weather.
In California, it is a violation of § 4442 or § 4443 of the Public Resources Code to use or operate gasoline-powered tools on forest-covered, brush-covered or grass-covered land unless the engine’s exhaust system is equipped with a complying spark arrester that is maintained in effective working order. The owner/operator of this product is responsible for properly maintaining the spark arrester. Other states or governmental entities/agencies, such as the U.S. Forest Service, may have similar requirements. Contact your local fire agency or forest service for the laws or regulations relating to fire protection requirements.
Keep the chain, bar and sprocket clean; replace worn sprockets or chains. Keep the chain sharp. You can spot a dull chain when easy-to-cut wood becomes

hard to cut and burn marks appear on the wood. Keep the chain at proper tension.
Tighten all nuts, bolts and screws except the carburetor adjustment screws after each use.
WARNING
In order for the chain brake on your STIHL chain saw to properly perform its function of reducing the risk of kickback and other injuries, it must be properly maintained. Like an automobile brake, a chain saw chain brake incurs wear each time it is engaged.
The amount of wear will vary depending upon usage, conditions under which the saw is used and other factors. Excessive wear will reduce the effectiveness of the chain brake and can render it inoperable.
For the proper and effective operation of the chain brake, the brake band and clutch drum must be kept free of dirt, grease and other foreign matter which may reduce friction of the band on the drum.
For these reasons, each STIHL chain saw should be returned to trained personnel such as your STIHL servicing dealer for periodic inspection and servicing of the brake system according to the following schedule:
Heavy usage ­ every three months, Moderate usage ­ twice a year, Occasional usage ­ annually.

The chain saw should also be returned immediately for maintenance whenever the brake system cannot be thoroughly cleaned or there is a change in its operating characteristics.
For any maintenance of the emission control system please refer to the maintenance chart and to the limited warranty statement near the end of the instruction manual.
Do not clean your machine with a pressure washer. The solid jet of water may damage parts of the machine.
Store chain saw in a dry place and away from children. Before storing for longer than a few days, always empty the fuel tank (see chapter “Storing the Machine” in the instruction manual).

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MS 660

Reactive Forces
Reactive Forces including Kickback
WARNING Reactive forces may occur any time the chain is rotating. Reactive forces can cause serious personal injury.
The powerful force used to cut wood can be reversed and work against the operator. If the rotating saw chain is suddenly and significantly slowed or stopped by contact with any solid object such as a log or branch or is pinched, the reactive forces may occur instantly. These reactive forces may result in loss of control, which, in turn, may cause serious or fatal injury. An understanding of the causes of these reactive forces may help you avoid the element of surprise and loss of control. Surprise contributes to accidents. The most common reactive forces are: ­ kickback, ­ pushback, ­ pull-in.

001BA257 KN 001BA035 KN

WARNING Kickback:
Kickback may occur when the moving saw chain near the upper quadrant of the bar nose contacts a solid object or is pinched. When this occurs, the energy driving the saw chain can create a force that moves the chain saw in a direction opposite to the saw chain movement at the point where the saw chain is slowed or stopped. This may fling the bar up and back in a lightning fast reaction mainly in the plane of the bar and can cause severe or fatal injury to the operator.
Kickback may occur, for example, when the saw chain near the upper quadrant of the bar nose contacts the wood or is

English
pinched during limbing or when it is incorrectly used to begin a plunge or boring cut.
The greater the force of the kickback reaction, the more difficult it becomes for the operator to control the chain saw. Many factors influence the occurrence and force of the kickback reaction. These include saw chain speed, the speed at which the bar and saw chain contact the object, the angle of contact, the condition of the saw chain and other factors.
The type of bar and saw chain you use is an important factor in the occurrence and force of the kickback reaction. Some STIHL bar and saw chain types are designed to reduce kickback forces. STIHL recommends the use of reduced kickback bars and low kickback chains.
Chain Saw Standard
The following standard applies:
­ § 5.11 of ANSI/OPEI B175.1-2012
This standard, in the following referred to as ‘the chain saw standard’ sets certain performance and design criteria related to chain saw kickback.
To comply with the chain saw standard:
a) Chain saws with a displacement of less than 3.8 cubic inches (62 cm³)

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English
­ must, in their original condition, meet a 45° computer derived kickback angle when equipped with certain cutting attachments,
­ and must be equipped with at least two devices to reduce the risk of kickback injury, such as a chain brake, low kickback saw chain, reduced kickback bar, etc.
b) Chain saws with a displacement of 3.8 cubic inches (62 cm³) and above
­ must be equipped with at least one device designed to reduce the risk of kickback injury, such as a chain brake, low kickback saw chain, reduced kickback bar, etc.
The computer derived angles for chain saws below 3.8 cubic inches (62 cm³) displacement are measured by applying a computer program to test results from a kickback test machine.
WARNING
The computer derived angles of the chain saw standard may bear no relationship to actual kickback bar rotation angles that may occur in real life cutting situations.
In addition, features designed to reduce kickback injuries may lose some of their effectiveness when they are no longer in their original condition, especially if they have been improperly maintained. Compliance with the chain saw standard does not automatically mean that in a real life kickback the bar and saw chain will rotate at most 45°.

WARNING
In order for chain saws below 3.8 cubic inches (62 cm³) displacement to comply with the computed kickback angle requirements of the chain saw standard use only the following cutting attachments:
­ bar and saw chain combinations listed as complying in the “Specifications” section of the instruction manual or
­ other replacement bar and saw chain combinations marked in accordance with the standard for use on the chain saw or
­ replacement saw chain designated “low kickback saw chain.”
See the section on “Low kickback saw chain and reduced kickback bars.”
Devices for Reducing the Risk of Kickback Injury
Stihl recommends the use of green labeled reduced kickback bars and low kickback saw chains on your chain saw equipped with a Stihl Quickstop chain brake.
WARNING
To reduce the risk of injury, never use a chain saw if the chain brake does not function properly. Take the chain saw to your local STIHL servicing dealer. Do not use the chain saw until the problem has been rectified.

STIHL Quickstop Chain Brake
STIHL has developed a saw chain stopping system designed to reduce the risk of injury in certain kickback situations. It is called a Quickstop chain brake.

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MS 660

There are two mechanisms which could induce braking under the conditon that the brake is in a properly maintained condition:
­ manual activation: If a kickback occurs, the chain saw moves upwards towards the user in a rotating motion around the front handle. The brake is engaged once the hand contacts the front guard, which is the activtion lever for the brake.
­ inertia activation: All STIHL chain saws are equipped with an interia Quickstop chain brake. If the kickback impulse is strong enough, this alone is sufficient to engage the brake even without contacting the front hand guard.

001BA174 KN

WARNING
Never operate your chain saw without a front hand guard. In a kickback situation this guard helps protect your left hand and other parts of your body. In addition, removal of the hand guard on a chain saw equipped with a Quickstop chain brake will disable the activation mechanism of the chain brake.
WARNING
No Quickstop or other chain brake device prevents kickback. These devices are designed to reduce the risk of kickback injury, if activated, in certain kickback situations. In order for the Quickstop to reduce the risk of kickback injury, it must be properly maintained and in good working order. See the chapter of your instruction manual entitled “Chain Brake” and the section “Maintenance, Repair and Storing” at the end of these Safety Precautions. In addition, there must be enough distance between the bar and the operator to ensure that the Quickstop has sufficient time to activate and stop the chain before potential contact with the operator.
WARNING
An improperly maintained chain brake may increase the time needed to stop the saw chain after activation, or may not activate at all.
WARNING
Never run the chain saw above idle speed for more than 3 seconds when the chain brake is engaged or when the saw

English
chain is pinched or otherwise caught in the cut. Clutch slippage can cause excessive heat, leading to severe damage of the motor housing, clutch and oiler component and may interfere with the operation of the chain brake. If clutch slippage in excess of 3 seconds has occurred, allow the motor housing to cool before proceeding and check the operation of your chain brake as described in the chapter entitled “Chain Brake” of your instruction manual. Also make sure that the saw chain is not turning at idle speed (see above at “Important Adjustments”).
Low Kickback Saw Chain and Reduced Kickback Bars
STIHL offers a variety of bars and saw chains. STIHL reduced kickback bars and low kickback saw chains are designed to reduce the risk of kickback injury. Other saw chains are designed to achieve higher cutting performance or sharpening ease, but in turn are more prone to kickback.
STIHL has developed a color code system to help you identify the STIHL reduced kickback bars and low kickback saw chains. Cutting attachments with green warning decals or green labels on the packaging are designed to reduce the risk of kickback injury. The matching of green decaled chain saws under 3.8 cubic inches (62 cm³) displacement with green labeled bars and green labeled saw chains gives compliance with the computed kickback angle requirements of the chain saw standard when the products are in their original condition. Products with yellow decals or labels are for users with extraordinary

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English
cutting needs, having experience and specialized training for dealing with kickback..
STIHL recommends the use of its green labeled reduced kickback bars, green labeled low kickback saw chains and a chain saw equipped with a STIHL Quickstop chain brake for both experienced and inexperienced chain saw users.
Please ask your STIHL dealer to properly match your chain saw with the appropriate bar / saw chain combination to reduce the risk of kickback injury. Green labeled bars and saw chains are recommended for all chain saws.
WARNING
Use of other, non-listed bar / saw chain combinations may increase kickback forces and the risk of kickback injury. New bar / saw chain combinations may be developed after publication of this literature, which will, in combination with certain chain saws, comply with the chain saw standard as well. Check with your STIHL dealer for such combinations.
WARNING
Reduced kickback bars and low kickback saw chains do not prevent kickback, but they are designed to reduce the risk of kickback injury. They are available from your STIHL dealer.
WARNING
Even if your saw is equipped with a Quickstop, a reduced kickback bar and / or low kickback saw chain, this does not

eliminate the risk of injury by kickback. Therefore, always observe all safety precautions to avoid kickback situations.
Low Kickback Saw Chain
Some types of saw chains have specially designed components to reduce the force of nose contact kickback. STIHL has developed low kickback saw chain for your chain saw.
A “low kickback saw chain” is a saw chain that has met the kickback performance requirements of ANSI/OPEI B175.1-2012 when tested according to the provisions specified in ANSI/OPEI B175.1-2012.
WARNING
There are potential chain saw and bar combinations with which low kickback saw chains can be used which have not been specifically certified to comply with the 45° computer derived kickback angle of the chain saw standard. Some low kickback saw chains have not been tested with all chain saw and bar combinations.
WARNING
A blunt or incorrectly sharpened saw chain may reduce or negate the effects of the design features intended to reduce kickback energy. Improper lowering or sharpening of the depth gauges as well as changing the shape of the cutters may increase the risk and the energy of kickback. Always cut with a properly sharpened saw chain.

Reduced Kickback Bars
STIHL green labeled reduced kickback bars are designed to reduce the risk of kickback injury when used with STIHL green labeled low kickback saw chains.
WARNING
When used with other, more aggressive saw chains, these bars may be less effective in reducing kickback.
WARNING
For a properly balanced saw and in order to comply with the chain saw standard, use only bar lengths listed in the specifications chapter of the instruction manual for your chain saw.
To avoid kickback
The best protection from personal injury that may result from kickback is to avoid kickback situations:
1. Hold the chain saw firmly with both hands and maintain a secure grip. Don’t let go.
2. Be aware of the location of the guide bar nose at all times.
3. Never let the nose of the guide bar contact any object. Do not cut limbs with the nose of the guide bar. Be especially careful near wire fences and when cutting small, tough limbs, small size brush and saplings which may easily catch the saw chain.
4. Don’t overreach.
5. Don’t cut above shoulder height.
6. Begin cutting and continue at full throttle.

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7. Cut only one log at a time.
8. Use extreme caution when reentering a previous cut.
9. Do not attempt to plunge cut if you are not experienced with these cutting techniques.
10. Be alert for shifting of the log or other forces that may cause the cut to close and pinch the saw chain.
11. Maintain saw chain properly. Cut with a correctly sharpened, properly tensioned saw chain at all times.
12. Stand to the side of the cutting path of the chain saw.
Bow Guides
WARNING
Do not mount a bow guide on any STIHL chain saw. Any chain saw equipped with a bow guide is potentially very dangerous. The risk of kickback is increased with a bow guide because of the increased kickback contact area. Low kickback saw chain will not significantly reduce the risk of kickback injury when used on a bow guide.

A = Pull-in
A
Pull-in occurs when the saw chain on the bottom of the bar is suddenly stopped when it is pinched, caught or encounters a foreign object in the wood. The reaction of the saw chain pulls the chain saw forward and may cause the operator to lose control. Pull-in frequently occurs when the bumper spike of the chain saw is not held securely against the tree or limb and when the saw chain is not rotating at full speed before it contacts the wood.
WARNING Use extreme caution when cutting small size brush and saplings which may easily catch the saw chain, be whipped towards you or pull you off balance. To avoid pull-in 1. Always start a cut with the saw
chain rotating at full speed and the bumper spike in contact with the wood. 2. The risk of pull-in may also be reduced by using wedges to open the kerf or cut.

001BA037 KN 001BA038 KN

B = Pushback

English

B
Pushback occurs when the saw chain on the top of the bar is suddenly stopped when it is pinched, caught or encounters a foreign object in the wood. The reaction of the saw chain may drive the chain saw rapidly straight back toward the operator and may cause loss of chain saw control, which, in turn, may cause serious or fatal injury. Pushback frequently occurs when the top of the bar is used for cutting.
To avoid pushback
1. Be alert to forces or situations that may cause material to pinch the top of the saw chain.
2. Do not cut more than one log at a time.
3. Do not twist the chain saw when withdrawing the bar from a plunge cut or underbuck cut because the saw chain can pinch.

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Working Techniques

Bucking

Limbing

Limbing is removing the branches from a fallen tree.
WARNING
There is an extreme danger of kickback during the limbing operation. Do not work with the nose of the bar. Be extremely cautious and avoid contacting the log or other limbs with the nose of the guide bar.
Do not stand on a log while limbing it ­ you may slip or the log may roll.
Start limbing by leaving the lower limbs to support the log off the ground. When underbucking freely hanging limbs, a pinch may result or the limb may fall, causing loss of control. If a pinch occurs, stop the engine and remove the saw by lifting the limb.
WARNING
Be extremely cautious when cutting limbs or logs under tension (spring poles). The limbs or logs could spring back toward the operator and cause loss of control of the saw and severe or fatal injury to the operator.

Bucking is cutting a log into sections.
WARNING
When bucking, do not stand on the log. Make sure the log will not roll downhill. If on a slope, stand on the uphill side of the log. Watch out for rolling logs.
Cut only one log at a time.
Shattered wood should be cut very carefully. Sharp slivers of wood may be caught and flung in the direction of the operator of the saw.

001BA033 KN
001BA051 LÄ

When cutting small logs, place log through “V”-shaped supports on top of a sawhorse. Never permit another person to hold the log. Never hold the log with your leg or foot.

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MS 660

1
2
2
1
Logs under strain: Risk of pinching! Always start relieving cut (1) at compression side.Then make bucking cut (2) at tension side. If the saw pinches, stop the engine and remove it from the log. Only properly trained professionals should work in an area where the logs, limbs and roots are tangled. Working in “blow down” areas is extremely hazardous. Drag the logs into a clear area before cutting. Pull out exposed and cleared logs first. Felling

001BA152 KN

001BA151 KN

WARNING
There are a number of factors that may affect and change the intended direction of fall, e.g. wind direction and speed, lean of tree, surrounding trees and obstacles, sloping ground, one-sided limb structure, wood structure, decay, snow load, etc. To reduce the risk of severe or fatal injury to yourself or others, look for these conditions prior to beginning the cut, and be alert for a change in direction while the tree is falling.
WARNING
Always observe the general condition of the tree. Inexperienced users should never attempt to cut trees that are decayed or rotted inside or that are leaning or otherwise under tension. There is an increased risk that such trees could snap or split while being cut and cause serious or fatal injury to the operator or bystanders. Also look for broken or dead branches which could vibrate loose and fall on the operator. When felling on a slope, the operator should stand on the uphill side if possible.

Felling Instructions

English

001BA088 LÄ

1

1/2

1

21/2

When felling, maintain a distance of at least 2 1/2 tree lengths from the nearest person.
When felling in the vicinity of roads, railways and power lines, etc., take extra precautions. Inform the police, utility company or railway authority before beginning to cut.

WARNING
The noise of your engine may drown any warning call.

Felling is cutting down a tree.
Before felling a tree, consider carefully all conditions which may affect the direction of fall.

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21

English Escape Path
A

Buttress Roots

Conventional Cut

B
C 45°

001BA146 KN

If the tree has large buttress roots, cut

45°

into the largest buttress vertically first

(horizontally next) and remove the

resulting piece.

C

B

Gunning Sight

001BA143 KN

001BA040 KN

First clear the tree base and work area from interfering limbs and brush and clean its lower portion with an ax.
Then, establish two paths of escape (B) and remove all obstacles. These paths should be generally opposite to the planned direction of the fall of the tree (A) and about at a 45° angle. Place all tools and equipment a safe distance away from the tree, but not on the escape paths.

When making the felling notch, use the gunning sight on the shroud and housing to check the desired direction of fall:
Position the saw so that the gunning sight points exactly in the direction you want the tree to fall.

001BA153 KN

Felling notch (C) ­ determines the direction of the fall
For a conventional cut:
N Properly place felling notch perpendicular to the line of fall, close to the ground.
N Cut down at approx. 45° angle to a depth of about 1/5 to 1/4 of the trunk diameter.
N Make second cut horizontal.
N Remove resulting 45° piece.

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MS 660

Open-face Technique

Making Sapwood Cuts

D =Felling Cut

English
D

D

001BA150 KN 001BA144 KN

Felling notch (C) ­ determines the direction of the fall
For an open-face cut:
N Properly place felling notch perpendicular to the line of fall, close to the ground.
N Cut down at approx. 50° angle to a depth of approx.1/5 to 1/4 of the trunk diameter.
N Make second cut from below at approx. 40 degree angle.
N Remove resulting 90° piece.

N For medium sized or larger trees make cuts at both sides of the trunk, at same height as subsequent felling cut.
N Cut to no more than width of guide bar.
This is especially important in softwood in summer ­ it helps prevent sapwood splintering when the tree falls.

Conventional and open-face technique:
N Begin 1 to 2 inches (2,5 to 5 cm) higher than center of felling notch.
N Cut horizontally towards the felling notch.
N Leave approx.1/10 of diameter uncut. This is the hinge.
N Do not cut through the hinge ­ you could lose control of the direction of the fall.
Drive wedges into the felling cut where necessary to control the fall.
WARNING
If the tip of the bar contacts a wedge, it may cause kickback. Wedges should be of wood or plastic ­ never steel, which can damage the chain.

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English E = Hinge
E
E

Felling Cut for Small Diameter Trees: Simple Fan Cut

Felling Cut for Large Diameter Trees

1

001BA145 KN 001BA147 KN
001BA148 KN

N Helps control the falling tree.
N Do not cut through the hinge ­ you could lose control of the direction of the fall.

Engage the bumper spikes of the chain saw directly behind the location of the intended hinge and pivot the saw around this point only as far as the hinge. The bumper spike rolls against the trunk.

WARNING
Felling a tree that has a diameter greater than the length of the guide bar requires use of either the sectioning felling cut or plunge-cut method. These methods are extremely dangerous because they involve the use of the nose of the guide bar and can result in kickback. Only properly trained professionals should attempt these techniques.
Sectioning Method
For the sectioning method make the first part of the felling cut with the guide bar fanning in toward the hinge. Then, using the bumper spike as a pivot, reposition the saw for the next cut.

24

MS 660

English

2
4
Avoid repositioning the saw more than necessary. When repositioning for the next cut, keep the guide bar fully engaged in the kerf to keep the felling cut straight. If the saw begins to pinch, insert a wedge to open the cut. On the last cut, do not cut the hinge. Plunge-cut Method Timber having a diameter more than twice the length of the guide bar requires the use of the plunge-cut method before making the felling cut. First, cut a large, wide felling notch. Make a plunge cut in the center of the notch.

The plunge cut is made with the guide bar nose. Begin the plunge cut by applying the lower portion of the guide bar nose to the tree at an angle. Cut until the depth of the kerf is about the same as the width of the guide bar. Next, align the saw in the direction in which the recess is to be cut. With the saw at full throttle, insert the guide bar in the trunk.
Enlarge the plunge cut as shown in the illustration.
WARNING There is an extreme danger of kickback at this point. Extra caution must be taken to maintain control of the saw. To make the felling cut, follow the sectioning method described previously. If you are inexperienced with a chain saw, plunge-cutting should not be attempted. Seek the help of a professional.

WARNING
In order to reduce the risk of personal injury, never stand directly behind the tree when it is about to fall, since part of the trunk may split and come back towards the operator (barber-chairing), or the tree may jump backwards off the stump. Always keep to the side of the falling tree. When the tree starts to fall, withdraw the bar, shut off the engine and walk away on the preplanned escape path. Watch out for falling limbs.
WARNING
Be extremely careful with partially fallen trees which are poorly supported. When the tree hangs or for some other reason does not fall completely, set the saw aside and pull the tree down with a cable winch, block and tackle or tractor. If you try to cut it down with your saw, you may be injured.

MS 660

25

English
Cutting Attachment

Chain scabbard

Fitting chain scabbard extension

A cutting attachment consists of the saw chain, guide bar and chain sprocket.
The cutting attachment that comes standard is designed to exactly match the chain saw.
1 2

001BA248 KN

a

3

­ The pitch (t) of the saw chain (1), chain sprocket and the nose sprocket of the Rollomatic guide bar must match.
­ The drive link gauge (2) of the saw chain (1) must match the groove width of the guide bar (3).
If non-matching components are used, the cutting attachment may be damaged beyond repair after a short period of operation.

Your saw comes standard with a chain scabbard that matches the cutting attachment.
If you use guide bars of different lengths on the saw, the length of the chain scabbard must be matched to the guide bar to reduce the risk of injury. It should cover the full length of the guide bar.
The length of the matching guide bars is marked on the side of the chain scabbard.
Chain scabbard extensions
One chain scabbard extension is required for guide bars longer than 35.4 in (90 cm). Two extensions are required for guide bars longer than 47.2 in (120 cm).
Depending on original equipment, the chain scabbard extension either comes with the machine or is available as a special accessory.

001BA244 KN

13

2

001BA249 KN

3
N Push the chain scabbard extension (1) and chain scabbard (2) together, making sure the locking tabs (3) engage in the chain scabbard
3
3
N If more than one chain scabbard extension is required, push the second chain scabbard extension and the first chain scabbard extension together, making sure the locking tabs (3) engage in the first chain scabbard extension

001BA250 KN

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MS 660

Mounting the Bar and Chain

Disengaging the chain brake.

Removing the chain sprocket cover

English

3

11

24

001BA187 KN

001BA186 KN

N Unscrew the nuts and take off the chain sprocket cover.
1
2
N Turn the screw (1) counterclockwise until the tensioner slide (2) butts against the left end of the housing slot.

001BA185 KN

143BA034 KN

N Pull the hand guarad towards the front handle until there is an audible click ­ the chain brake is disengaged.
Fitting the chain
WARNING Wear work gloves to protect your hands from the sharp cutters. N Fit the chain ­ start at the bar nose.

143BA003 KN

N Fit the guide bar over the studs (1) ­ the cutting edges on the top of the bar must point to the right.
N Engage the peg of the tensioner slide in the locating hole (2) ­- place the chain over sprocket (3) at the same time.
N Turn the tensioning screw (4)clockwise until there is very little chain sag on the underside of the bar ­ and the drive link tangs are engaged in the bar groove.
N Refit the sprocket cover and screw on the nuts only fingertight.
N Go to chapter on “Tensioning the Saw Chain”

MS 660

27

English

Tensioning the Chain

Checking Chain Tension

Fuel

1
Retensioning during cutting work: N Shut off the engine. N Loosen the nuts. N Hold the bar nose up. N Use a screwdriver to turn the
tensioning screw (1) clockwise until the chain fits snugly against the underside of the bar. N While still holding the bar nose up, tighten down the nuts firmly. N Go to “Checking Chain Tension”. A new chain has to be retensioned more often than one that has been in use for some time. N Check chain tension frequently ­ see chapter on “Operating Instructions”.

133BA024 KN 143BA007 KN

N Shut off the engine.
N Wear work gloves to protect your hands.
N The chain must fit snugly against the underside of the bar and it must still be possible to pull the chain along the bar by hand.
N If necessary, retension the chain.
A new chain has to be retensioned more often than one that has been in use for some time.
N Check chain tension frequently ­ see chapter on “Operating Instructions”.

This engine is certified to operate on unleaded gasoline and the STIHL twostroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of highquality gasoline and two-stroke air cooled engine oil.
Use mid-grade unleaded gasoline with a minimum octane rating of 89 ((R+M)/2) and no more than 10% ethanol content.
Fuel with a lower octane rating may increase engine temperatures. This, in turn, increases the risk of piston seizure and damage to the engine.
The chemical composition of the fuel is also important. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as well. This could cause running problems or even damage the engine. For this reason STIHL recommends that you use only high-quality unleaded gasoline!
Gasoline with an ethanol content of more than 10% can cause running problems and major damage in engines and should not be used.
The ethanol content in gasoline affects engine running speed ­ it may be necessary to readjust the carburetor if you use fuels with various ethanol contents.
WARNING
To reduce the risk of personal injury from loss of control and/or contact with the running cutting tool, do not use your

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MS 660

unit with incorrect idle adjustment. At correct idle speed, the cutting tool should not move.
If your power tool shows an incorrect idle adjustment, have your STIHL dealer check your power tool and make proper adjustments and repairs.
The idle speed and maximum speed of the engine change if you switch from a fuel with a certain ethanol content to another fuel with a much higher or lower ethanol content.
This problem can be avoided by always using fuel with the same ethanol content.
Use only STIHL two-stroke engine oil or equivalent high-quality two-stroke engine oils that are designed for use only in air cooled two-cycle engines.
We recommend STIHL HP Ultra 2-Cycle Engine Oil since it is specially formulated for use in STIHL engines.
Do not use BIA or TCW rated (twostroke water cooled) mix oils or other mix oils that state they are for use in both water cooled and air cooled engines (e.g., outboard motors, snowmobiles, chain saws, mopeds, etc.).
WARNING
Take care when handling gasoline. Avoid direct contact with the skin and avoid inhaling fuel vapor. When filling at the pump, first remove the container from your vehicle and place the container on the ground before filling. To reduce the risk of sparks from static discharge and resulting fire and/or explosion, do not fill fuel containers that are sitting in or on a vehicle or trailer.

The container should be kept tightly closed in order to limit the amount of moisture that gets into the mixture.
The machine`s fuel tank should be cleaned as necessary.
Fuel mix ages

Only mix sufficient fuel for a few days work, not to exceed 30 days of storage. Store in approved fuel-containers only. When mixing, pour oil into the container first, and then add gasoline. Close the container and shake it vigorously by hand to ensure proper mixing of the oil with the fuel.

Gasoline US gal. 1 2 1/2 5

Oil (STIHL 50:1 or equivalent high-quality oils) US fl.oz. 2.6 6.4 12.8

Dispose of empty mixing-oil containers only at authorized disposal locations.

Fueling
Preparations

English

143BA000 KN

N Before fueling, clean the filler cap and the area around it to ensure that no dirt falls into the tank.
Always thoroughly shake the mixture in the canister before fueling your machine. N Position the machine so that the
filler cap is facing up.
WARNING
In order to reduce the risk of fire and personal injury from escaping gas vapor and fumes, remove the fuel filler cap carefully so as to allow any pressure build-up in the tank to release slowly.
WARNING
After fueling, tighten fuel cap as securely as possible by hand.

MS 660

29

English Change the fuel pickup body

Chain Lubricant

Filling Chain Oil Tank

Change the fuel pickup body every year.
N Open the filler cap and drain the fuel tank.
N Use a hook to pull the fuel pickup body out of the tank and take it off the hose.
NOTICE
Do not kink the fuel hose ­ do not use any sharp or pointed tools.
N Push the new pickup body into the hose.
N Place the pickup body in the tank and close the filler cap.

143BA009 KN 001BA158 KN

For automatic and reliable lubrication of the chain and guide bar ­ use only an environmentally compatible quality chain and bar lubricant. Rapidly biodegradable STIHL BioPlus is recommended.
NOTICE
Biological chain oil must be resistant to aging (e.g. STIHL BioPlus), since it will otherwise quickly turn to resin. This results in hard deposits that are difficult to remove, especially in the area of the chain drive and chain. It may even cause the oil pump to seize.
The service life of the chain and guide bar depends on the quality of the lubricant. It is therefore essential to use only a specially formulated chain lubricant.
WARNING
Do not use waste oil. Renewed contact with waste oil can cause skin cancer. Moreover, waste oil is environmentally harmful.
NOTICE
Waste oil does not have the necessary lubricating properties and is unsuitable for chain lubrication.

Preparing the machine
N Thoroughly clean the filler cap and the area around it to ensure that no dirt falls into the tank
N Always position the machine so that the filler cap is facing upwards
N Open the filler cap Filling Chain Oil Tank
Standard oil pump N Refill the chain oil tank every time
you refuel Oil pump with increased delivery rate (available option) Frequent checking and refilling of the oil tank is necessary ­ see “Adjusting oil quantity”. N Refill the chain oil tank when the fuel
tank is approximately half empty

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MS 660

All versions
Take care not to spill chain oil during refilling and do not overfill the tank.
N Close the filler cap
There must still be a small amount of chain oil in the oil tank when the fuel tank is empty.
If the oil tank is still partly full, the reason may be a problem in the oil supply system: Check chain lubrication, clean the oil passages, contact your servicing dealer for assistance if necessary. STIHL recommends that maintenance and repair work be carried out only by authorized STIHL dealers.

Checking Chain Lubrication

Chain Brake

English

Locking chain with chain brake

143BA024 KN 143BA011 KN

MS 660

The saw chain must always throw off a small amount of oil.
NOTICE
Never operate your saw without chain lubrication. If the chain runs dry, the whole cutting attachment will be irretrievably damaged within a very short time. Always check chain lubrication and the oil level in the tank before starting work.
Every new chain has to be broken in for about 2 to 3 minutes.
After breaking in the chain, check chain tension and adjust if necessary ­ see “Checking Chain Tension”.

­ in an emergency
­ when starting
­ at idling speed
The chain is stopped and locked when the hand guard is pushed toward the bar nose by the left hand ­ or when brake is activated by inertia in certain kickback situations.

31

English Releasing the chain brake

felling cut. The chain brake will operate only if it has been properly maintained and the hand guard has not been modified in any way.
Check operation of chain brake

Winter Operation

Before starting work: Run engine at idle speed, engage the chain brake (push hand guard toward bar nose). Accelerate up to full throttle for no more than 3 seconds ­ the chain must not rotate. The hand guard must be free from dirt and move freely.
Chain brake maintenance

At temperatures below +50 °F (+10 °C) N Remove the carburetor box cover
1

143BA012 KN
137BA014 KN

N Pull the hand guard back toward the front handle.
NOTICE
Always disengage chain brake before accelerating engine and before starting cutting work. The only exception to this rule is when you check operation of the chain brake.
High revs with the chain brake engaged (chain locked) will quickly damage the powerhead and chain drive (clutch, chain brake).
The chain brake is designed to be activated also by the inertia of the front hand guard
if the forces are sufficiently high. The hand guard is accelerated toward the bar nose – even if your left hand is not behind the hand guard, e.g. during a

The chain brake is subject to normal wear. It is necessary to have it serviced and maintained regularly by trained personnel, such as your STIHL servicing dealer, at the following intervals:

Full-time usage: Part-time usage: Occasional usage:

every 3 months
every 6 months
every 12 months

2
N in the carburetor box cover, move the slide (1) from summer position to winter position (2)
Heated air is now drawn in from around the cylinder and mixed with cold air ­ this helps prevent carburetor icing.
NOTICE Above +70 °F (+20 °C): Always return the cover to the position for “summer operation” again! Risk of engine malfunction ­ overheating! N Replace the carburetor box cover
and tighten the knob
Air filter system
N Retrofit new air filter if necessary ­ see “Air filter system”

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MS 660

At temperatures below +14 °F (-10 °C)

Electric Handle Heating

English
Starting / Stopping the Engine
Positions of Master Control Lever

137BA015 KN 137BA016 KN
001BA140 KN

Switching on the handle heating system (depending on equipment version)

STOP

Under extreme winter conditions (temperatures below +14 °F (-10 °C), powdered or drifting snow), it is recommended to mount the cover plate (special accessory) on the fan housing.
The partial covering of the slits in the fan housing keeps out powdered or drifting snow.
When the cover plate is mounted, the slide must be in winter position in the carburetor box cover.
N If the chain saw is extremely cold (frost formation) ­ after starting, bring the engine up to operating temperature at increased idle speed (disengage chain brake!)
N If engine trouble occurs, first check whether use of the cover plate is necessary

N To switch on, set switch to F and to switch off, return switch to the 0 position
Overheating during continuous use is impossible. The heating system is maintenance-free.

0
Stop 0 ­ engine off ­ the ignition is switched off Normal run position (F) ­ engine runs or can fire. Starting throttle (n) ­ this position is used to start a warm engine. The Master Control lever moves to the normal run position as soon as the throttle trigger is squeezed. Choke shutter closed (l) ­ this position is used to start a cold engine.

MS 660

33

English Setting the Master Control Lever

Holding the Saw

Between knees or thighs

To move the Master Control lever from the normal run position (F) to choke closed (l), press down the throttle trigger lockout and squeeze the throttle trigger at the same time and hold them in that position ­ now set the Master Control lever.
To select the starting throttle position (n), move the Master Control lever to choke closed (l) first, then push it into the starting throttle position (n).
The Master Control lever must be in the choke closed position (l) for the changeover to the starting throttle position (n).
The Master Control lever moves from the starting throttle position (n) to the run position (F) when you press down the throttle trigger lockout and blip the throttle trigger at the same time.
To switch off the engine, move the Master Control lever to Stop (0).
Choke shutter closed (l)
­ if the engine is cold
­ if the engine stalls when you open the throttle after starting.
­ if the fuel tank was run until empty (engine stopped).
Starting throttle position (n)
­ if the engine is warm, i.e. if it has been running for about one minute.
­ after engine begins to fire,
­ after clearing a flooded combustion chamber.

There are two ways of holding the saw when starting. On the ground
N Place your saw on the ground. Make sure you have a firm footing ­ check that the chain is not touching any object or the ground.
N Hold the saw firmly on the ground with your left hand on the front handle ­ your thumb should be under the handle.
N Put your right foot into the rear handle and press down.

143BA018 KN 143BA019 KN

N Hold the rear handle tightly between your legs, just above the knees.
N Hold the front handle firmly with your left hand ­ your thumb should be under the handle.

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MS 660

Cranking

Starting the Saw
WARNING Bystanders must be well clear of the general work area of the saw.

English
STOP
0
1

2 4
3

143BA020 KN
133BA001 K
178BA007 KN

N Pull the starter grip slowly with your right hand until you feel it engage ­ and then give it a brisk strong pull and push down the front handle at the same time. Do not pull out the starter rope to full length ­ it might otherwise break. Do not let the starter grip snap back. Guide it slowly back into the housing so that the starter rope can rewind properly.
Machines without additional manual fuel pump: If the engine is new or after a long out-of-service period, it may be necessary to pull the starter rope several times to prime the fuel system.

N Press in the button to open the decompression valve.
The decompression valve closes as soon as the engine fires. For this reason you must press in the button before each starting attempt.

N Push the hand guard (1) forward ­ the chain is locked.
N Press down the trigger lockout (2) and pull the throttle trigger (3) at the same time. Set Master Control lever (4) to:
Choke shutter closed (l)
­ if the engine is cold (also use this position if the engine stopped when you opened the throttle after starting)
Starting throttle position (n)
­ if the engine is warm, i.e. if it has been running for about one minute.
N Hold and start your saw as described.

MS 660

35

English When engine begins to fire
STOP
0
1
N Set the Master Control lever (1) to the starting throttle position (n).
N Press the button to open the decompression valve.
N Hold and start your saw as described.
As soon as the engine runs
STOP
0
1 2
N Press down trigger lockout and the blip the throttle trigger (2) ­ the Master Control lever (1) moves to the run position (F) and the engine settles down to idling speed.

178BA009 KN

178BA008 KN 001BA186 KN

N Pull the hand guard back toward the front handle.
The chain brake is now disengaged ­ your saw is ready for operation.
NOTICE
Always disengage chain brake before accelerating the engine. High revs with the chain brake engaged (chain locked) will quickly damage the clutch and chain brake.
At very low outside temperatures

position (n) quickly enough after the engine began to fire, the combustion chamber may be flooded.
N Move the Master Control lever to the stop position (0).
N Remove the spark plug ­ see “Spark Plug”.
N Dry the spark plug.
N Crank the engine several times with the starter to clear the combustion chamber.
N Refit the spark plug ­ see “Spark Plug”.
N Set Master Control lever to the starting throttle position (n) ­ even if the engine is cold.
N Press the button to open the decompression valve.
N Now start the engine.

N Allow engine to warm up at part throttle.
N Change over to winter operation if necessary ­ see “Winter Operation”.
Stopping the engine

N Move the Master Control lever to the stop position (0).
If engine does not start

If you did not move the Master Control lever from the choke closed position (l) to the starting throttle

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MS 660

Operating Instructions
During the break-in period
A factory new machine should not be run at high revs (full throttle off load) for the first three tank fillings. This avoids unnecessarily high loads during the break-in period. As all moving parts have to bed in during the break-in period, the frictional resistances in the shortblock are greater during this period. The engine develops its maximum power after about 5 to 15 tank fillings.
During work
NOTICE Do not make the mixture leaner to achieve an apparent increase in power ­ this could damage the engine ­ see “Adjusting the Carburetor”.
NOTICE Open the throttle only when the chain brake is off. Running the engine at high revs with the chain brake engaged (chain locked) will quickly damage the shortblock and chain drive (clutch, chain brake).
Check chain tension frequently
A new saw chain must be retensioned more frequently than one that has been in use already for an extended period.

Chain cold
Tension is correct when the chain fits snugly against the underside of the bar but can still be pulled along the bar by hand. Retension if necessary ­ see “Tensioning the Saw Chain”.
Chain at operating temperature
The chain stretches and begins to sag. The drive links must not come out of the bar groove on the underside of the bar ­ the chain may otherwise jump off the bar. Retension the chain ­ see “Tensioning the Saw Chain”.
NOTICE
The chain contracts as it cools down. If it is not slackened off, it can damage the crankshaft and bearings.
After a long period of full-throttle operation
After a long period of full-throttle operation, allow engine to run for a while at idle speed so that the heat in the engine can be dissipated by flow of cooling air. This protects enginemounted components (ignition, carburetor) from thermal overload.
After finishing work
N Slacken off the chain if you have retensioned it at operating temperature during work.

English
NOTICE Always slacken off the chain again after finishing work. The chain contracts as it cools down. If it is not slackened off, it can damage the crankshaft and bearings.
Short-term storage
Wait for engine to cool down. Keep the machine with a full tank of fuel in a dry place, well away from sources of ignition, until you need it again.
Long-term storage
See “Storing the machine”

MS 660

37

English
Oil Quantity Control

Oil pump with increased delivery rate (available option)

Taking Care of the Guide Bar

Varying cutting lengths, types of wood and working techniques require varying quantities of oil.
Standard oil pump
1
The oil delivery rate can be adjusted as needed using the adjusting screw (1) (on the bottom of the machine). Ematic setting (E), moderate oil delivery rate ­ N Turn adjusting screw to “E” (Ematic
setting) Increase oil delivery rate ­ N Turn the adjusting screw clockwise Reduce oil delivery rate ­ N Turn the adjusting screw
counterclockwise NOTICE The saw chain must always be coated with chain oil.

001BA157 KN
143BA026 KN

The oil pump with increased delivery rate can be identified by the groove (2) in the adjusting screw.
With this oil pump, in setting range a, the oil tank can run empty before the fuel tank, thus causing the saw chain to run dry.
N in setting range a, fill the fuel tank only half full or refill the oil tank when the fuel tank is approximately half empty

2

1

3

N Turn the guide bar over ­ every time you sharpen the chain and every time you replace the chain ­ this helps avoid one-sided wear, especially at the nose and underside of the bar.
N Regularly clean the oil inlet hole (1), the oilway (2) and the bar groove (3).
N Measure the groove depth ­ with the scale on the filing gauge (special accessory) ­ in the area used most for cutting.

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MS 660

Chain type Picco Rapid Picco Rapid Rapid

Chain pitch
1/4″ P 1/4″ 3/8″ P 3/8″; 0.325″ 0.404″

Minimum groove depth 0.16″ (4.0 mm) 0.16″ (4.0 mm) 0.20″ (5.0 mm) 0.24″ (6.0 mm) 0.28″ (7.0 mm)

If groove depth is less than specified:

N Replace the guide bar.

The drive link tangs will otherwise scrape along the bottom of the groove ­ the cutters and tie straps will not ride on the bar rails.

Air Filter System
The air filter system can be adapted to different operating conditions by the insertion of different air filters. Retrofitting is simple.

English
Fouled air filters will impair engine performance, increase fuel consumption and make the machine more difficult to start.

001BA210 KN

N HD2-Filter (black filter frame. folded filter fabric) Universal filter for almost all conditions of use (from very dusty to wintry conditions etc.)

001BA212 KN

N Wire mesh filter (green filter housing) Use in extra-ordinary conditions e.g. extremely wintry conditions of use – such as powder snow or drift snow. Rather unsuitable in very dusty conditions.
When dry, STIHL filters attain a long service life.
N Always use STIHL filters dry

MS 660

39

English

Remove air filter

Cleaning the Air Filter

Engine Management

N Turn the knob above the rear handle in the direction of the arrow and remove the carburetor box cover
N Remove filter

145BA028 K

145BA027 K

If there is a noticeable loss of engine power:
N Knock out the filter or blow it clear with compressed air from the inside outwards
If knocking-out or blowing-out does not suffice, or in the case of stubborn dirt or stuck filter fabric, the filter must be subjected to a thorough cleaning.
Always replace a damaged filter.
Thorough filter cleaning
N Wash the filter in STIHL specialpurpose cleaner (special accessory) or a clean, nonflammable cleaning liquid (e.g., warm soapy water) ­ rinse the filter from inside to out under a water jet ­ do not use high-pressure cleaners
N Dry all filter parts ­ do not expose to extreme heat
N Do not oil the filter
N Reinstall filter

Exhaust emissions are controlled by the design of the fundamental engine parameters and components (e.g. carburation, ignition, timing and valve or port timing) without the addition of any major hardware.

40

MS 660

Adjusting the Carburetor
General Information
The carburetor comes from the factory with a standard setting. This setting provides an optimum fuel-air mixture under most operating conditions. Changing the setting of the high speed screw alters the engine’s power output and the maximum off-load engine speed.
Standard Setting
N Shut off the engine. N Check the air filter and clean or
replace if necessary. N Check the spark arresting screen
(not in all models, country-specific) in the muffler and clean or replace if necessary.

Carburetors with H = 1 and L = 1

HL

176BA008 KN

N Carefully screw both adjusting screws down onto their seats (clockwise).
N Turn the high speed screw (H) one full turn counterclockwise.
N Turn the low speed screw (L) one full turn counterclockwise.
Carburetors with H = 3/4 and L = 1/4

HL

HL

137BA023 KN

N Turn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn).
N Turn the low speed screw (L) carefully clockwise as far as stop, then turn it back 1/4 turn.

Adjusting Idle Speed

English

N Carry out the standard setting. N Start and warm up the engine.

137BA024 KN

L
LA
Engine stops while idling N Turn the idle speed screw (LA)
clockwise until the chain begins to run ­ then back it off 1/4 turn.
Saw chain runs while engine is idling N Turn the idle speed screw (LA)
counterclockwise until the chain stops moving ­ then turn it another 1/4 turn in the same direction.
WARNING If the chain continues moving when the engine is idling, have your saw checked and repaired by your servicing dealer.
Erratic idling behavior, poor acceleration (even though standard setting of low speed screw is correct) Idle setting is too lean N Turn the low speed screw (L)
counterclockwise, no further than stop on carburetors with L = 1/4, until the engine runs and accelerates smoothly.

MS 660

41

178BA010 KN

English
It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L).
Fine Tuning for Operation at High Altitude
A slight correction of the setting may be necessary if engine does not run satisfactorily: N Carry out the standard setting. N Warm up the engine. N Turn the high speed screw (H)
slightly clockwise (leaner). On carburetors with H = 3/4, turn no further than stop.
NOTICE
After returning from high altitude, reset the carburetor to the standard setting.
If the setting is too lean there is a risk of engine damage due to insufficient lubrication and overheating.

Spark Arresting Screen in Muffler
In some countries, the muffler is fitted with a spark arresting screen. N If engine performance deteriorates,
check the spark arresting screen in the muffler N Let the muffler cool down Version A
1
N Remove four screws N Remove exhaust casing (1) of the
muffler
3 2

137BA025 KN

N Clean the dirty spark arresting screen, replace if damaged or heavily carbonized
N Refit the spark arresting screen in reverse order of steps
Version B
In this version, the muffler is equipped with two spark arresting screens.
1 2
N Remove screw (1) N Lift and pull out the spark arresting
screen (2) N Clean the dirty spark arresting
screen, replace if damaged or heavily carbonized N Refit the spark arresting screen in reverse order of steps N Check second spark arresting screen ­ as with Version A

137BA026 KN

N Bend back the retaining lugs (2) N Pull out spark arresting screen (3)

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MS 660

English

Spark Plug
If engine is down on power, difficult to start or runs poorly at idling speed, first check the spark plug. Fit a new spark plug after approx. 100 operating hours or earlier if the electrodes are badly eroded. Wrong fuel mix (too much engine oil in the gasoline), a dirty air filter and unfavorable running conditions (mostly at part throttle etc.) affect the condition of the spark plug. These factors cause deposits to form on the insulator nose which may result in trouble in operation.
Remove the spark plug
N Move the Master Control lever to the stop position 0
N Turn the knob above the rear handle in the direction of the arrow and remove the carburetor box cover

137BA008 KN

1 2
N Lift the air baffle (1) up and off N Unplug spark plug boot (2) N Unscrew spark plug Checking the Spark Plug
A
N Clean dirty spark plug. N Check electrode gap (A) and
readjust if necessary ­ see “Specifications.” N Use only resistor type spark plugs of the approved range. Rectify problems that have caused fouling of spark plug: ­ too much oil in fuel mix, ­ dirty air filter, ­ unfavorable running conditions, e.g. operating at part load.

000BA039 KN

137BA009 KN

1
2
WARNING To reduce the risk of fire and burn injury, use only spark plugs authorized by STIHL. Always press spark plug boot (1) snugly onto spark plug terminal (2) of the proper size. (Note: If terminal has detachable SAE adapter nut, it must be securely attached.) A loose connection between spark plug boot and ignition wire connector in the boot may create arcing that could ignite combustible fumes and cause a fire. Install spark plug
N Screw in the spark plug and press on the spark plug boot
N Install air baffle N Mount carburetor box cover

000BA071 KN

MS 660

43

English

Rewind Starter
To help prolong the wear life of the starter rope, observe the following points:
N Pull the starter rope only in the direction specified.
N Do not pull the rope over the edge of the guide bushing.
N Do not pull out the rope more than specified.
N Do not allow the starter grip to snap back, guide it back into the housing slowly ­ see chapter on “Starting / Stopping the Engine.”
Have a damaged starter rope replaced by your dealer before it breaks completely. STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.

Storing the Machine
For periods of 3 months or longer
N Drain and clean the fuel tank in a well ventilated area.
N Dispose of fuel properly in accordance with local environmental requirements.
N Run the engine until the carburetor is dry ­ this helps prevent the carburetor diaphragms sticking together.
N Remove the saw chain and guide bar, clean them and spray with corrosion inhibiting oil.
N Thoroughly clean the machine ­ pay special attention to the cylinder fins and air filter.
N If you use a biological chain and bar lubricant, e.g. STIHL BioPlus, completely fill the chain oil tank.
N Store the machine in a dry, high or locked location, out of the reach of children and other unauthorized persons.

Checking and Replacing the Chain Sprocket
N Remove chain sprocket cover, saw chain and guide bar.
N Release chain brake ­ pull hand guard against the front handle
Fit new chain sprocket
­ after use of two saw chains or earlier
­ if the wear marks (arrows) are deeper than 0.02 in (0.5 mm) ­ otherwise the service life of the saw chain is reduced ­ use check gauge (special accessory) to test
Using two saw chains in alternation helps preserve the chain sprocket. Use only STIHL original chain sprockets to help ensure reliable functioning of the chain brake.

001BA121 KN

44

MS 660

5
62 1
4
3
6 2 1
N Use a screwdriver to remove the Eclip (1)
N Remove the washer (2) N Remove rim sprocket (3) (if so
equipped), clutch drum (4) and needle cage (6). N Inspect transport profile for rim sprocket on the clutch drum (4) ­ if there are also heavy signs of wear, also replace the clutch drum N Remove clutch drum with integrated spur chain sprocket (5) (if so equipped) including needle cage (6) from the crankshaft ­ for powerheads with Quickstop Plus chain brake system, depress throttle trigger lockout beforehand

001BA122 KN

Install spur chain sprocket / rim sprocket
N Clean crankshaft stub and needle cage and lubricate with STIHL lubricant (special accessory)
N Slide needle cage onto the crankshaft stub
N After refitting, turn the clutch drum and/or spur chain sprocket approx. 1 full turn so that the carrier for the oil pump drive engages
N Refit the rim sprocket ­ cavities toward the outside
N Refit washer and E-clip on the crankshaft

English
Maintaining and Sharpening the Saw Chain
Sawing effortlessly with a properly sharpened saw chain
A properly sharpened saw chain cuts through wood effortlessly even with very little pushing.
Never use a dull or damaged saw chain ­ this leads to increased physical strain, increased vibration load, unsatisfactory cutting results and increased wear. N Clean the saw chain N Check the saw chain for cracks and
damaged rivets N Replace damaged or worn chain
components and adapt these parts to the remaining parts in terms of shape and level of wear ­ rework accordingly
Carbide-tipped (Duro) saw chains are especially wear-resistant. For an optimal sharpening result, STIHL recommends STIHL servicing dealers.
WARNING
Compliance with the angles and dimensions listed below is absolutely necessary. An improperly sharpened saw chain ­ especially depth gauges that are too low ­ can lead to increased kickback tendency of the chain saw ­ risk of injury!

MS 660

45

English Chain pitch

Sharpening and side plate angles

File holder

A
a

689BA027 KN 689BA021 KN 689BA025 KN

B

The chain pitch marking (a) is embossed in the area of the depth gauge of each cutter.

Marking (a)
7 1 or 1/4 6, P or PM 2 or 325 3 or 3/8 4 or 404

Chain pitch

Inches mm

1/4 P 6.35

1/4

6.35

3/8 P 9.32

0.325 8.25

3/8

9.32

0.404 10.26

The diameter of file to be used depends on the chain pitch ­ see table “Sharpening tools”.

The angles of the cutter must be maintained during resharpening.

A Sharpening angle
STIHL saw chains are sharpened with a 30° sharpening angle. Ripping chains, which are sharpened with a 10° sharpening angle, are exceptions. Ripping chains have an X in the designation.
B Side plate angle
The correct side plate angle results automatically when the specified file holder and file diameter are used.

Tooth shapes
Micro = semi-chisel tooth, e. g., 63 PM3, 26 RM3, 36 RM Super = full chisel tooth, e. g., 63 PS3, 26 RS, 36 RS3 Ripping chain, e. g., 63 PMX, 36 RMX

Angle (°) AB 30 75
30 60
10 75

The angles must be identical for all cutters in the saw chain. Varying angles: Rough, uneven running of the saw chain, increased wear ­ even to the point of saw chain breakage.

N Use a file holder Always use a file holder (special accessory, see table “Sharpening tools”) when sharpening saw chains by hand. File holders have markings for the sharpening angle. Use only special saw chain files! Other files are unsuitable in terms of shape and type of cutting.
To check the angles
STIHL filing gauge (special accessory, see table “Sharpening tools”) ­ a universal tool for checking sharpening and side plate angles, depth gauge setting, and tooth length, as well as cleaning grooves and oil inlet holes.

001BA203 KN

46

MS 660

Proper sharpening
N Select sharpening tools in accordance with chain pitch
N Clamp guide bar if necessary N Block saw chain ­ push the hand
guard forward N To advance the saw chain, pull the
hand guard toward the handlebar: The chain brake is disengaged. With the Quickstop Plus chain brake system, additionally press the throttle trigger lockout N Sharpen frequently, removing little material ­ two or three strokes of the file are usually sufficient for simple resharpening
90°

689BA018 KN

markings on the file holder ­ rest the file holder on the tooth head and the depth gauge
N File only from the inside outward
N The file only sharpens on the forward stroke ­ lift the file on the backstroke
N Do not file tie straps and drive links
N Rotate the file a little periodically in order to avoid uneven wear
N To remove file burr, use a piece of hardwood
N Check angle with file gauge
All cutters must be equally long.
With varying cutter lengths, the cutter heights also vary and cause rough running of the saw chain and chain breakage.
N All cutters must be filed down equal to the length of the shortest cutter ­ ideally, one should have this done by a servicing dealer using an electric sharpener
Depth gauge setting

English

a Required distance between depth gauge and cutting edge
When cutting softwood outside of the frost season, the distance can be increased by up to 0.2 mm (0.008″).

Chain pitch

Inches 1/4 P 1/4 3/8 P 0.325 3/8 0.404

(mm) (6.35) (6.35) (9.32) (8.25) (9.32) (10.26)

Depth gauge Distance (a) mm (Inches) 0.45 (0.018) 0.65 (0.026) 0.65 (0.026) 0.65 (0.026) 0.65 (0.026) 0.80 (0.031)

Lowering the depth gauges

The depth gauge setting is lowered when the cutter is sharpened.
N Check the depth gauge setting after each sharpening

1

2

689BA061 KN

N Guide the file: horizontally (at a right angle to the side surface of the guide bar) in accordance with the specified angle ­ according to the

689BA043 KN

a
The depth gauge determines the depth to which the cutter penetrates the wood and thus the chip thickness.

689BA023 KN

N Lay the appropriate file gauge (1) for the chain pitch on the saw chain and press it against the cutter to be checked ­ if the depth gauge protrudes past the file gauge, the depth gauge must be reworked

MS 660

47

English
Saw chains with humped drive link (2) ­ upper part of the humped drive link (2) (with service mark) is lowered at the same time as the depth gauge of the cutter.

689BA051 KN 689BA044 KN 689BA052 KN

WARNING

The rest of the humped drive link must not be filed; otherwise, this could increase the tendency of the chain saw to kick back.

N Afterwards, dress the leading edge of the depth gauge parallel to the service mark (see arrow) ­ when doing this, be careful not to further lower the highest point of the depth gauge

WARNING
Depth gauges that are too low increase the kickback tendency of the chain saw.

N Rework the depth gauge so that it is flush with the file gauge

Sharpening tools (special accessories)

Chain pitch

Round file ^ Round file

File holder

File gauge

N Lay the file gauge on the saw chain ­ the highest point of the depth gauge must be flush with the file gauge
N After sharpening, clean the saw chain thoroughly, removing any filings or grinding dust ­ lubricate the saw chain thoroughly
N In the event of extended periods of disuse, store saw chains in cleaned and oiled condition
Taper square file Sharpening set

Inches (mm) mm (Inches) Part number

Part number

Part number

1/4 P (6.35) 3.2 (1/8) 5605 771 3206 5605 750 4300 0000 893 4005

1/4

(6.35) 4.0 (5/32) 5605 772 4006 5605 750 4327 1110 893 4000

3/8 P (9.32) 4.0 (5/32) 5605 772 4006 5605 750 4327 1110 893 4000

0.325 (8.25) 4.8 (3/16) 5605 772 4806 5605 750 4328 1110 893 4000

3/8

(9.32) 5.2 (13/64) 5605 772 5206 5605 750 4329 1110 893 4000

0.404 (10.26) 5.5 (7/32) 5605 772 5506 5605 750 4330 1106 893 4000 1) consisting of file holder with round file, taper square file and file gauge

Part number 0814 252 3356 0814 252 3356 0814 252 3356 0814 252 3356 0814 252 3356 0814 252 3356

Part number 5605 007 1000 5605 007 1027 5605 007 1027 5605 007 1028 5605 007 1029 5605 007 1030

48

MS 660

Maintenance and Care
The following information applies under normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal each day or under difficult conditions (extensive dust, highly resinous lumber, lumber from tropical trees, etc.). If the machine is only used occasionally, the intervals can be extended accordingly.

English

Before starting work At the end of work and/or daily Whenever tank is refilled Weekly Monthly Yearly If faulty If damaged As required

Complete machine Throttle trigger, throttle trigger lockout, choke lever, choke control, stop switch, master control lever (dependent on equipment) Chain brake
Manual fuel pump (if present)
Fuel pick-up body / filter in fuel tank
Fuel tank Lubricating oil tank Chain lubrication
Saw chain
Guide bar
Chain sprocket Air filter

Visual inspection (condition, leaks) Clean
Function tests
Function tests Have checked by a specialist dealer1) Check Have repaired by a specialist dealer1) Check Clean, replace filter insert Replace Clean Clean Check Check, pay attention to sharpness Check chain tension Sharpen Check (wear, damage) Clean and turn over Deburr Replace Check Clean Replace

MS 660

X

X

X

X

X

X

X

X

X

X

X

X

X

X

XX

X

X

X

X

X

X

X

X

X

X

X

XX

X

X

X

X

49

English
The following information applies under normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal each day or under difficult conditions (extensive dust, highly resinous lumber, lumber from tropical trees, etc.). If the machine is only used occasionally, the intervals can be extended accordingly.

Before starting work At the end of work and/or daily Whenever tank is refilled Weekly Monthly Yearly If faulty If damaged As required

Anti-vibration elements

Check

X

Have them replaced by a servicing dealer1)

Air intake on fan housing

Clean

X

X

Cylinder fins

Clean

X

X

Carburetor

Check idle adjustment ­ saw chain must not rotate

X

X

Set the idle speed, have the chain saw repaired by a servicing dealer1)

Spark plug

Adjust electrode gap Replace after 100 hours of operation

All accessible screws, nuts and bolts (not adjusting screws)

Tighten2)

Have checked by a specialist dealer1)

Spark arresting screen in muffler

Have cleaned by a specialist dealer, or replaced if necessary1)

Check

X

Chain catcher

Replace

Exhaust bore

Decarbonise after 139 hours of operation, subsequently after every 150 hours of operation

Safety information label

Replace

X X X
X X
X X
X
X X
X

1. STIHL recommends STIHL servicing dealers 2) During initial use of professional chain saws (with a power output of 3.4 kW or more), tighten the cylinder block screws after 10 to 20 hours of operation

50

MS 660

Main Parts

2 1

3

10

7

4

6

8

11

5 9

12

15 14

16
17 18

13

20

22

23

21

19

24

English
1 Carburetor Box Cover Twist Lock 2 Spark Plug Boot 3 Carburetor Adjusting Screws 4 Handle Heating Switch (Depending
on Model) 5 Chain Sprocket Cover 6 Chain Sprocket 7 Chain Brake 8 Chain Tensioner 9 Chain Catcher 10 Bumper Spike 11 Guide Bar 12 Oilomatic Saw Chain 13 Oil Filler Cap 14 Muffler with Spark Arresting Screen 15 Front Hand Guard 16 Front Handle (Handlebar) 17 Decompression Valve
(Automatically Resetting) 18 Starter Grip 19 Fuel Filler Cap 20 Master Control Lever 21 Throttle Trigger 22 Throttle Trigger Lockout 23 Rear Handle 24 Rear Hand Guard # Serial Number

178BA004 KN

MS 660

51

English
Definitions
1 Carburetor Box Cover Twist Lock Lock for carburetor box cover.
2 Spark Plug Boot Connects the spark plug with the ignition lead.
3 Carburetor Adjusting Screws For tuning the carburetor.
4 Handle Heating Switch (Depending on Model) For switching the electric handle heating on and off.
5 Chain Sprocket Cover Covers the clutch and chain sprocket.
6 Chain Sprocket The toothed wheel that drives the saw chain.
7 Chain Brake A device to stop the rotation of the chain. Is activated in a kickback situation by the operator’s hand or by inertia.
8 Chain Tensioner Permits precise adjustment of chain tension.
9 Chain Catcher Helps to reduce the risk of operator contact by a chain when it breaks or comes off the bar.
10 Bumper Spike Toothed stop for holding saw steady against wood.
11 Guide Bar Supports and guides the saw chain.

12 Oilomatic Saw Chain A loop consisting of cutters, tie straps and drive links.
13 Oil Filler Cap For closing the oil tank.
14 Muffler with Spark Arresting Screen Muffler reduces engine exhaust noise and diverts exhaust gases away from operator. Spark arresting screen is designed to reduce the risk of fire.
15 Front Hand Guard Provides protection against projecting branches and helps prevent left hand from touching the chain if it slips off the handlebar. It also serves as the lever for chain brake activation.
16 Front Handle (Handlebar) Handlebar for the left hand at the front of the saw.
17 Decompression Valve (Automatically Resetting) Releases compression pressure to make engine starting easier ­ when activated.
18 Starter Grip The grip of the pull starter, for starting the engine.
19 Fuel Filler Cap For closing the fuel tank.
20 Master Control Lever Lever for choke control, starting throttle, run and stop switch position.
21 Throttle Trigger Controls the speed of the engine.

22 Throttle Trigger Lockout Must be depressed before the throttle trigger can be activated.
23 Rear Handle The support handle for the right hand, located at the rear of the saw.
24 Rear Hand Guard Gives added protection to operator’s right hand.
Guide Bar Nose The exposed end of the guide bar. (not illustrated, see chapter “Tensioning the Saw Chain”)
Clutch Couples engine to chain sprocket when engine is accelerated beyond idle speed. (not illustrated)
Anti-Vibration System The anti-vibration system includes a number of anti- vibration elements designed to reduce the transmission of vibrations created by the engine and cutting attachment to the operator’s hands. (not illustrated)

52

MS 660

Specifications

EPA / CEPA

The Emission Compliance Period referred to on the Emissions Compliance Label indicates the number of operating hours for which the engine has been shown to meet Federal emission requirements.
Category
A = 300 hours B = 125 hours C = 50 hours
Engine

STIHL single cylinder two-stroke engine

MS 660

Displacement:

5.6 cu. in. (91.6 cm3)

Bore:

2.13 in. (54 mm)

Stroke:

1.57 in. (40 mm)

Engine power to ISO 7.0 hp (5.2 kW)

7293:

bei 9,500 rpm

Idle speed:

2,500 rpm

High speed setting

when performing

repairs (with bar and

chain):

13,500 rpm

Ignition System

Spark plug (resistor NGK BPMR 7 A,

type):

Bosch WSR 6 F

Electrode gap:

0.02 in (0.5 mm)

Fuel System

All position diaphragm carburetor with integral fuel pump Fuel tank capacity: 27.9 fl.oz (0.825 l)
Chain Lubrication

Fully automatic, speed-controlled oil pump with rotary piston. Additional manual oil flow control
Oil tank capacity: 12.2 fl.oz (0.36 l)
Weight

dry, without bar and chain

MS 660:

16.5 lbs. (7.5 kg)

MS 660 with wraparound handle: 16.8 lbs. (7.6 kg)

Cutting Attachment

Recommended cutting attachments complying with Section 5.11 of ANSI/OPEI B 175.1-2012
Observe notes on ANSI/OPEI B 175.1-2012 and definition of “low kickback chain” in chapter on “Safety Precautions and Working Techniques”.

Electronic (breakerless) magneto ignition

English

Rollomatic E guide bars

Reduced kickback STIHL guide bar (with green label)

Cutting lengths:

20, 25, 28, 32 or 36 in (50, 63, 70, 80 or 90 cm)

Pitch:

3/8″ (9.32 mm)

Groove width: 0.050 in (1.3 mm)

Nose sprocket: 10-tooth

Reduced kickback STIHL guide bar (with green label)

Cutting lengths:

20, 22, 25, 28, 32 or 36 in (50, 55, 63, 70, 80 or 90 cm)

Pitch:

3/8″ (9.32 mm)

Groove width: 0.063 in (1.6 mm)

Nose sprocket: 10-tooth

3/8″ chains

Low kickback STIHL saw chain (with green label)

Rapid Super 3 (33 RS3) Type 3624

Pitch:

3/8″ (9.32 mm)

Drive link gauge: 0.050 in (1.3 mm)

Low kickback STIHL saw chain (with green label)

Rapid Super 3 (36 RS3) Type 3626

Pitch:

3/8″ (9.32 mm)

Drive link gauge: 0.063 in (1.6 mm)

Chain sprocket

7-tooth for 3/8″ (rim sprocket)
To ensure compliance with the kickback properties required in Section 5.11 of ANSI B 175.1-2000, only use replacement chains that, when used with this specific powerhead, comply

MS 660

53

English
with Section 5.11 of the ANSI standard or are classed as “low kickback” chains according to ANSI B 175.1-2000.
Please ask your STIHL dealer for the latest recommendations on new bar/chain combinations developed after publication of this instruction manual.

Special Accessories
Contact your STIHL dealer for information regarding special accessories that may be available for your product.

Ordering Spare Parts
Please enter your saw model, serial number as well as the part numbers of the guide bar and saw chain in the spaces provided. This will make reordering simpler. The guide bar and saw chain are subject to normal wear and tear. When purchasing these parts, always quote the saw model, the part numbers and names of the parts. Model
Serial number
Guide bar part number
Chain part number
See “Specifications” in this manual for the recommended reduced kickback cutting attachments.

54

MS 660

English

Maintenance and Repairs
Users of this unit should carry out only the maintenance operations described in this manual. STIHL recommends that other repair work be performed only by authorized STIHL servicing dealers.
Warranty claims following repairs can be accepted only if the repair has been performed by an authorized STIHL servicing dealer using original STIHL replacement parts.
Original STIHL parts can be identified by the STIHL part number, the { logo and, in some cases, by the STIHL parts symbol K. The symbol may appear alone on small parts.

Disposal
Observe all country-specific waste disposal rules and regulations.
STIHL products must not be thrown in the garbage can. Take the product, accessories and packaging to an approved disposal site for environmentfriendly recycling. Contact your STIHL servicing dealer for the latest information on waste disposal.

000BA073 KN

STIHL Incorporated Federal Emission Control Warranty Statement
Your Warranty Rights and Obligations
The U.S. Environmental Protection Agency (EPA) and STIHL Incorporated are pleased to explain the Emission Control System Warranty on your equipment type engine. In the U.S. new 1997 and later model year small off-road equipment engines must be designed, built and equipped, at the time of sale, to meet the U.S. EPA regulations for small non road engines. The equipment engine must be free from defects in materials and workmanship which cause it to fail to conform with U.S. EPA standards for the first two years of engine use from the date of sale to the ultimate purchaser.
STIHL Incorporated must warrant the emission control system on your small off- road engine for the period of time listed below provided there has been no abuse, neglect or improper maintenance of your small off-road equipment engine.
Your emission control system includes parts such as the carburetor and the ignition system. Also included may be hoses, and connectors and other emission-related assemblies.
Where a warrantable condition exists, STIHL Incorporated will repair your small off-road equipment engine at no cost to you including diagnosis (if the diagnostic work is performed at an authorized dealer), parts and labor.

MS 660

55

English
Manufacturer’s Warranty Coverage
In the U.S., 1997 and later model year small off-road equipment engines are warranted for two years. If any emissionrelated part on your engine is defective, the part will be repaired or replaced by STIHL Incorporated free of charge.
Owner’s Warranty Responsibilities
As the small off-road equipment engine owner, you are responsible for the performance of the required maintenance listed in your instruction manual. STIHL Incorporated recommends that you retain all receipts covering maintenance on your small offroad equipment engine, but STIHL Incorporated cannot deny warranty solely for the lack of receipts or for your failure to ensure the performance of all scheduled maintenance.
Any replacement part or service that is equivalent in performance and durability may be used in non-warranty maintenance or repairs, and shall not reduce the warranty obligations of the engine manufacturer.
As the small off-road equipment engine owner, you should be aware, however, that STIHL Incorporated may deny you warranty coverage if your small off-road equipment engine or a part has failed due to abuse, neglect, improper maintenance or unapproved modifications.
You are responsible for presenting your small off-road equipment engine to a STIHL service center as soon as a

problem exists. The warranty repairs will be completed in a reasonable amount of time, not to exceed 30 days.
If you have any questions regarding your warranty rights and responsibilities, please contact a STIHL customer service representative at 1-800-4678445 or you can write to
STIHL Inc., 536 Viking Drive, P.O. Box 2015, Virginia Beach, VA 23450-2015
www.stihlusa.com
Coverage by STIHL Incorporated
STIHL Incorporated warrants to the ultimate purchaser and each subsequent purchaser that your small off-road equipment engine will be designed, built and equipped, at the time of sale, to meet all applicable regulations. STIHL Incorporated also warrants to the initial purchaser and each subsequent purchaser that your engine is free from defects in materials and workmanship which cause the engine to fail to conform with applicable regulations for a period of two years.
Warranty Period
The warranty period will begin on the date the utility equipment engine is purchased by the initial purchaser and you have signed and sent back the warranty card to STIHL.
If any emission-related part on your engine is defective, the part will be replaced by STIHL Incorporated at no cost to the owner. Any warranted part which is not scheduled for replacement

as required maintenance, or which is scheduled only for regular inspection to the effect of “repair or replace as necessary” will be warranted for the warranty period. Any warranted part which is scheduled for replacement as required maintenance will be warranted for the period of time up to the first scheduled replacement point for that part.
Diagnosis
You, as the owner, shall not be charged for diagnostic labor which leads to the determination that a warranted part is defective. However, if you claim warranty for a component and the machine is tested as non-defective, STIHL Incorporated will charge you for the cost of the emission test. Mechanical diagnostic work will be performed at an authorized STIHL servicing dealer. Emission test may be performed either at STIHL Incorporated or at any independent test laboratory.
Warranty Work
STIHL Incorporated shall remedy warranty defects at any authorized STIHL servicing dealer or warranty station. Any such work shall be free of charge to the owner if it is determined that a warranted part is defective.
Any manufacturer-approved or equivalent replacement part may be used for any warranty maintenance or repairs on emission-related parts and must be provided without charge to the owner. STIHL Incorporated is liable for

56

MS 660

damages to other engine components caused by the failure of a warranted part still under warranty. The following list specifically defines the emission- related warranted parts: ­ Air Filter ­ Carburetor (if applicable) ­ Fuel Pump ­ Choke (Cold Start Enrichment
System) (if applicable) ­ Control Linkages ­ Intake Manifold ­ Magneto or Electronic Ignition
System (Ignition Module or Electronic Control Unit) ­ Fly Wheel ­ Spark Plug ­ Injection Valve (if applicable) ­ Injection Pump (if applicable) ­ Throttle Housing (if applicable) ­ Cylinder ­ Muffler ­ Catalytic Converter (if applicable) ­ Fuel Tank ­ Fuel Cap ­ Fuel Line ­ Fuel Line Fittings ­ Clamps ­ Fasteners

Where to make a Claim for Warranty Service
Bring the product to any authorized STIHL servicing dealer and present the signed warranty card.
Maintenance Requirements
The maintenance instructions in this manual are based on the application of the recommended 2-stroke fuel-oil mixture (see also instruction “Fuel”). Deviations from this recommendation regarding quality and mixing ratio of fuel and oil may require shorter maintenance intervals.
Limitations
This Emission Control Systems Warranty shall not cover any of the following: N repair or replacement required
because of misuse, neglect or lack of required maintenance, N repairs improperly performed or replacements not conforming to STIHL Incorporated specifications that adversely affect performance and/or durability, and alterations or modifications not recommended or approved in writing by STIHL Incorporated,
and N replacement of parts and other
services and adjustments necessary for required maintenance at and after the first scheduled replacement point.

Trademarks

English

STIHL Registered Trademarks
STIHL® { K
The color combination orange-grey (U.S. Registrations #2,821,860; #3,010,057,

3,010,058, #3,400,477; and #3,400,476)

AUTOCUT® EASYSTART® FARM BOSS® iCademy® MAGNUM® MasterWrench Service® MotoMix®

MS 660

57

English
OILOMATIC® ROCK BOSS® STIHL Cutquik® STIHL DUROMATIC® STIHL Quickstop® STIHL ROLLOMATIC® STIHL WOOD BOSS® TIMBERSPORTS® WOOD BOSS® YARD BOSS®
Some of STIHL’s Common Law Trademarks
STIHL InjectionTM
4-MIX TM BioPlus TM Easy2Start TM EasySpool TM ElastoStart TM Ematic TM FixCut TM HT Plus TM IntelliCarb TM Master Control Lever TM Micro TM Pro Mark TM
58

Quad Power TM Quiet Line TM STIHL Arctic TM STIHL Compact TM STIHL HomeScaper Series TM STIHL Interchangeable Attachment Series TM STIHL M-Tronic TM STIHL MiniBoss TM STIHL MotoPlus 4 TM STIHL Multi-Cut HomeScaper Series TM STIHL OUTFITTERS TM STIHL PICCO TM STIHL PolyCut TM STIHL PowerSweep TM STIHL Precision Series TM STIHL Protech TM STIHL RAPID TM STIHL SuperCut TM STIHL Territory TM TapAction TM TrimCut TM This listing of trademarks is subject to change. Any unauthorized use of these trademarks without the express written consent of ANDREAS STIHL AG & Co. KG, Waiblingen is strictly prohibited.

MS 660

Contenido

español / EE.UU

Manual de instrucciones original

Las tintas contienen aceites vegetales, el papel es reciclable.

Impreso en papel libre de cloro.

Acerca de este manual de

instrucciones

60

Precauciones de seguridad

61

Fuerzas reactivas

75

Técnica de trabajo

81

Accesorio de corte

87

Montaje de la espada y la cadena 88

Tensado de la cadena

89

Revisión de tensión de la cadena 89

Combustible

89

Llenado de combustible

91

Lubricante de cadena

92

Llenado del tanque de aceite de la

cadena

92

Revisión de lubricación de la

cadena

93

Freno de la cadena

93

Manejo durante el invierno

94

Calefacción eléctrica de mango

95

Arranque / parada del motor

95

Instrucciones para el uso

99

Control de cantidad de aceite

100

Cuidado de la espada

100

Sistema de filtro de aire

101

Retiro de filtro de aire

102

Limpieza del filtro de aire

102

Gestión del motor

102

Ajuste del carburador

103

Chispero en el silenciador

104

Bujía

105

Dispositivo de arranque

106

Almacenamiento de la máquina 107

{

MS 660

Revisión y sustitución del piñón de

cadena

107

Mantenimiento y afilado de la

cadena de aserrado

108

Información para mantenimiento 112

Componentes importantes

114

Especificaciones

116

Accesorios especiales

117

Pedido de piezas de repuesto

117

Información de reparación

118

Desecho

118

Declaración de garantía de STIHL

Incorporated sobre sistemas de

control de emisiones según normas

Federales

118

Marcas comerciales

121

Permita que solamente las personas que comprenden la materia tratada en este manual manejen su motosierra.
Para obtener el rendimiento y satisfacción máximos de la motosierra STIHL, es importante que lea, comprenda y respete las medidas de seguridad y las instrucciones de uso y mantenimiento dadas en el capítulo “Medidas de seguridad y técnicas de uso”, antes de usar su motosierra. Para obtener información adicional, visite www.stihlusa.com.
Comuníquese con su representante de STIHL o el distribuidor de STIHL para su zona si no se entiende alguna de las instrucciones dadas en el presente manual.

ADVERTENCIA
Dado que la motosierra es una herramienta para cortar madera que funciona a gran velocidad, es necesario tomar medidas especiales de seguridad igual que con cualquier sierra motorizada, para reducir el riesgo de lesiones. El uso descuidado o inadecuado puede causar lesiones graves e incluso mortales.

Este manual de instrucciones está protegido por derechos de propiedad intelectual. Todos los derechos reservados, especialmente los derechos de reproducción, traducción y procesamiento con sistemas electrónicos.
59

© ANDREAS STIHL AG & Co. KG, 2013 0458-178-8621-B. VA8.M13. 0000001844_009_EA

español / EE.UU
Acerca de este manual de instrucciones
Este Manual de instrucciones corresponde a una motosierra STIHL, que aquí también está representada por el término “máquina”.
Pictogramas
Todos los pictogramas que se encuentran fijados o grabados en la máquina se explican en este manual. Según el modelo, los pictogramas siguientes pueden aparecer en su máquina.
Tanque de combustible; mezcla de gasolina y aceite de motor
Depósito de aceite de cadena; aceite de cadena
Aplicación y soltado del freno de la cadena STIHL Quickstop
Sentido de rotación de la cadena
Ematic; control de cantidad de aceite de cadena
Tensión de la cadena

Precalentamiento del aire de admisión para funcionamiento en invierno
Aire de admisión para funcionamiento en verano
Calentador de manillar
Uso de válvula de descompresión
Uso de bomba manual de combustible
Símbolos en el texto
Muchas de las instrucciones de uso y seguridad vienen acompañadas de ilustraciones. Los pasos individuales o procedimientos descritos en el manual pueden estar señalados en diferentes maneras: N Se usa un punto para denotar un
paso o procedimiento. Una descripción de un paso o procedimiento que se refiere directamente a una ilustración puede contener números de referencia que aparecen en la ilustración. Ejemplo: N Suelte el tornillo (1). N Palanca (2) …

Además de las instrucciones de uso, en este manual pueden encontrarse párrafos a los que usted debe prestar atención especial. Tales párrafos están marcados con los símbolos y las palabras identificadoras que se describen a continuación.
PELIGRO
Indica un riesgo inminente de lesiones graves o mortales.
ADVERTENCIA
Identifica una situación de peligro que, al no evitarse, puede resultar en lesiones graves o mortales.
INDICACIÓN
Indica el riesgo de daños a la propiedad, incluyendo a la máquina o sus componentes.
Mejoramientos técnicos
La filosofía de STIHL es mejorar continuamente todos sus productos. Como resultado de ello, periódicamente se introducen cambios de diseño y mejoras. Por lo tanto, es posible que algunos cambios, modificaciones y mejoras no se describen en este manual. Si las características de funcionamiento o la apariencia de su máquina difieren de las descritas en este manual, comuníquese con el concesionario STIHL para obtener la ayuda que requiera.

60

MS 660

Precauciones de seguridad
Dado que la motosierra es una herramienta motorizada que funciona a gran velocidad, es necesario tomar medidas especiales de seguridad para reducir el riesgo de lesiones.
Es importante que usted lea, comprenda bien y respete las siguientes advertencias y medidas de seguridad. Lea el manual de instrucciones y las instrucciones de seguridad periódicamente. El uso descuidado o inadecuado puede causar lesiones graves o incluso la muerte.
ADVERTENCIA
El uso de esta motosierra puede ser peligroso. La motosierra posee varios cortadores afilados. Si estos entran en contacto con alguna parte del cuerpo del operador, le causarán una herida, aunque la cadena esté detenida.
ADVERTENCIA
Las fuerzas reactivas, incluido el contragolpe, pueden ser peligrosas. Preste especial atención a la sección en la que se habla de las fuerzas reactivas.

Pida a su concesionario STIHL que le enseñe el manejo de la motosierra. Todas las medidas de seguridad que por lo general se toman cuando se trabaja con un hacha o sierra manual también son aplicables al manejo de las motosierras. Respete todas las disposiciones, reglamentos y normas de seguridad federales, estatales y locales del caso. Por ejemplo, cuando utilice una motosierra para cortar troncos, consulte los regl

References

• Country Routing Page: Welcome to STIHL | STIHL

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