SAITO FG-120TS Twin Petrol Engine Instruction Manual

: June 8, 2024
: SAITO

Table of Contents

SAITO FG-120TS Twin Petrol Engine
Specifications
Fuel
Ignition
Propeller
Break-in MOST IMPORTANT
Tappet adjustment
Warranty
Parts
Dimension
More Information
FAQ
References
Read User Manual Online (PDF format)
Download This Manual (PDF format)

SAITO FG-120TS Twin Petrol Engine

Specifications

Scale-2st 70cc-100cc class

---|---|---|---|---|---|---|---
Weight (Approx.)| Main body : 4,030 g / Muﬄers : 180g / Ignition : 160g| RPM range| Approx.1,000-6,000rpm| Max on ground| Approx. 5,500-6,000rpm
Propeller| 27” x 12“ ~28” x 12”| Plug| CM-6| Battery for ignition system| 6-12V, greater than 1,500mA (2~3S Lipo or LiFe) *20-25C

Recommended

Standard| •Limit gauge (0.1t) for tappet adjustment

•Spark plug[CM-6](Attached to the engine)

| 1pc

2pcs

| •Wrench for tappet adjusting lock nut

•Muﬄer set

| 1pc

1set

| •Carburetor adjustment bar

•Choke bar

| 1pc

1pc

accessories| •Ignition system (w/sensor)

•Stand oﬀ mount

| 1set 1set| •Muﬄer bracket

•Hexagonal wrench

| 1set 1pc| •Plug wrench| 1pc
Optional parts| •Filter with weight [G36-154] •Durable tube for Gasoline (1m) [G36-155]

•Tappet adjusting kit [120S-161] •Digital tachometer [G17-167]

Fuel

The fuel is a mixture of regular gasoline or high-octane gasoline and high-quality 2-stroke engine oil.
[Example of oil recommendation]
- Klotz KL-200 Original Techniplate
- Deluxe Materials PowerModel 2T-S
- ENEOS RACING SPEC PRO-2T (SAITO STANDARD) etc.
  If such oils are not available in your country, then please ask the oﬃcial SAITO distributor in your country for an alternative.
Be sure to use the mixture “gasoline: oil =15~20: 1” by volume ratio. (Ex. 1000ml of gasoline should be mixed with more than 50ml of oil ).
During the break-in process, use 15:1 mixed fuel to ensure the best lubrication for initial running.
Any damage caused by the fuel used, in which the oil ratio is lower than 20:1 will not be covered by warranty.
Do not use gasoline containing ethanol. It may cause not only power loss but also corrosion inside the engine.

Ignition

Ignition arrangement- Place the main unit as far from other electrical devices as possible.

Plug cord(meshed high-tension cord)
2 cords compatible with the left/right cylinder. Insert the cap deeply onto the plug to make sure it will not come oﬀ.
Sensor cord
Connect with the cord from the sensor attached to the engine.
Battery cord (black/red cord)
Use a fully charged battery that has adequate spec. (6-12V, more than 1500mA is recommended.). Between the battery and main unit, make sure to install a heavy-duty switch whose capacity is higher than 3A.
Tachometer cord (optional)
Connect the digital tachometer (Option). Otherwise, the connector is normally vacant.

Propeller

Recommended propeller is Mejzlik 27 x 12 which brings approx. 5,300rpm (or Falcon D27”xP12” brings approx. 5,000rpm).
Use a well-balanced one. Never use the propeller that has been scratched or damaged even if slightly.
Open a hole exactly in the propeller hub (boss) in advance as shown in the right ﬁgure using a drilling tool and propeller washer.
Pass the propeller through the shaft and tighten the six bolts inserting the propeller washer in the order of diagonal. ※The appropriate length of the bolts may be diﬀerent depending on the thickness of the propeller hub (boss). Depending on the propeller and spinner backplate you use, use M5 x 0.8 bolts with lengths that protrude 15～18mm. (Screw length of the standard accessory is 55mm)
As the propeller is compressed slightly, tighten the 6 bolts every hour of operation.

Method of choke (No need when you use starter)
Choking is the means by which fuel is fed to the engine when you start it by hand ﬂipping. Thus it is unnecessary when using starter. Starting with a electric starter is recommended for safety.

In advance, make a thin hole in the cowling to insert the choke bar / slow needle adjustment bar.
During choking, be sure to turn oﬀ the ignition switch.
As shown in the ﬁg, pass the choke bar (with M3.5 thread on its tip) through the hole in the cowling. Then turn the bar to insert it into the M3.5 internal thread at the center of the throttle lever.
Fully close the throttle and pull the choke bar and ﬁx it with a clip or clamp as shown in the ﬁg so that it may not go back to the previous position.
Grasp the prop by hand and turn it several times in the direction of normal operation (CCW) until the carburettor generates a hissing-like sound. After hearing this sound for about 5 times, quickly ﬂip the prop approximately 10 times. Remove the choke bar. Then power on the ignition system and ﬂip the prop quickly to start the engine. If the engine doesnʼt start, repeat the choking procedure.

Break-in MOST IMPORTANT

Before starting the engine, inject a suitable amount ( approx. 20cc ) of engine oil into the lubrication nipple on the crankcase using a syringe or pump while turning the propeller by hand. After that, plug this nipple. As excess is discharged from the breather nipple, attach a tube to the breather nipple.
Prop-recommendation: 27×12.
Use 15:1 fuel: oil ratio for break-in.
Never make the fuel mixture lean during Break-in. It could cause seizures even during idling or low-speed running.
Before starting the engine, open the main needle Approx. 3 turns open (CCW) from fully closed.
Start the engine (using a starter is recommended for safety).
Soon after starting, Open the throttle gradually up to over half open. In the meantime open the main needle CCW about 1~1.5 turns, keeping the throttle opened over half.
Soon after that open the slow needle CCW until RPM drops signiﬁcantly.
At this stage, single-cylinder operation (where one of the cylinders is misﬁring) is acceptable.
Run in this very rich condition for 1 liter of fuel.
Now “initial” break-in is done.

Adjustment of carburettor after initial break-in

Peak adjustment

After the initial break-in, keeping the main needle unchanged, open the slow needle Approx. 5 turns CCW from fully closed (Then throttle should be fully closed).
Start the engine (using a starter is recommended for safety).
Achieve the peak at full throttle.
Turn the main needle CW gradually to the position where the RPM is greatest (the peak). Turning over the needle CW past the peak could lead to a seizure so turn it slowly and carefully. Once the peak is passed, the RPM will drop suddenly. In that case immediately return (CCW) the main needle.
Once achieving peak RPM, return the throttle to low speed. Adjust the slow needle following the next chapter.

Slow needle Adjustment

After achieving peak, open the throttle from idle to full open quickly several times to check the response.
If the engine hesitates for a moment or stalls before the engine reaches max RPM, the mixture is too lean. Then turn the slow needle CCW slightly.
If the engine is slow to reach max RPM, the mixture is too rich. Then turn the slow needle CW slightly.
Adjust the slow needle in the above way until RPM follows the throttle movement smoothly. The important point is to adjust the slow needle in the condition where the main needle has been adjusted to its peak.
After the slow needle is adjusted, stop the engine and make a note of the main needle position at the peak. (So that you can refer to how many turns CCW from the fully closed position when you lost the right position.)

Pre-ﬂight / Flight adjustment

Before ﬂight open the main needle CCW more than a half turn from the peak position. (At least open the main needle 3 turns CCW from the position fully closed.) This is to make the fuel mixture richer in the air where the RPM get higher than on the ground.
After all adjustments are made, ﬂy your aircraft and ﬁne tune the engine according to the situation. Tuning should be done with the main needle. The slow needle also requires ﬁne tune when there is a large temperature diﬀerence, such as in summer and winter.
The break-in process and needle adjustment are done now. Proceed with the tappet adjustment using the following steps.
The best tune depends on various factors such as propeller, temperature, humidity, etc., so please adjust the needles according to the situation.

Tappet adjustment

The valve clearance should be checked and adjusted after a break-in and every time after two hours while the engine is cold. Before adjusting tappet gaps, tighten up the screws around cylinders etc.

Remove the spark plug and rocker arm covers of a cylinder. Then turn the prop CCW by hand to place the piston at the TDC of the compression stroke.
Loosen the lock nut and adjust the gap by a hexagonal wrench until you get the correct gap for both of intake & exhaust.
Once the gap is set, tighten the lock nut and attach the plug and covers. Then do the same adjustment for the other cylinder.
Turn the prop by hand to check if the compression is enough. If the gap is less than 0, the valve is always opened slightly and will lose compression. Then adjust again.

Note

Because it uses oil mixed with gasoline, the aircraft may become dirty due to exhaust smoke.
Use a reliable and well-balanced prop. Otherwise, it may cause an abnormal vibration and could result in a serious accident.
During operation, all engine screws can loosen due to metal heat expansion. Check and tighten occasionally.
When the exhaust valve gets dull by carbon or sludge, especially in a cold atmosphere, remove the rocker cover and apply some anti-rust spray to the exhaust valve. Then push and return several times to help the valve move smoothly.
Pay attention to the surroundings so as not to disturb others by noise and exhaust.
Always keep spectators behind the engine when operating the engine.
Exhaust smoke is harmful, so be careful not to inhale or expose yourself to it as much as possible. Otherwise, it may harm your health.
Pay attention not to touch the rotating propeller when starting the engine, and move to the rear side of the aircraft once the engine is started. All responsibilities for the use of the engine and other obligations and responsibilities based on laws, regulations, etc. are borne by the purchaser and the user. SAITO SEISAKUSHO CO., LTD. is exempt from any responsibilities.

Warranty

If there is any deﬁciency from the factory concerning manufacture, please consult with the shop or distributor you bought from. Our company will be responsible for repair. However, any failure or trouble caused by unnecessary disassembly, modiﬁcation, or other uses than those provided in the instruction manual is not subject to warranty.
The ignition system is subject to the warranty only for initial failure. Once the system has been activated successfully, it will no longer be subject

Parts

Dimension

All speciﬁcations and models are subject to change without notice.

More Information

SAITO SEISAKUSHO, CO., LTD. www.saito-mfg.com
22-7, 3-chrome, Tokagi, Ichikawa-shi, Chiba prefecture 272-0024, Japan
Phone: 047-378-4156
FAX: 047-378-4155

FAQ

Q: How do I troubleshoot if the product does not turn on?
- A: Check the power source and ensure the product is properly connected. If the issue persists, contact customer support for assistance.
Q: Can I use this product for outdoor activities?
- A: This product is suitable for indoor use only. Avoid exposing it to extreme weather conditions.