ngh GT25 2-Stroke RC Gasoline Engines Instruction Manual

ngh GT25 2-Stroke RC Gasoline Engines

Dear customer:
Thank you for purchasing our NGH GT25 gasoline engine. Professional GT25 engine has been developed by NGH engineers to offer all hobbyists gasoline engines. You will be delighted with fuel economy, reliability and power of your GT25. We hope that you will enjoy with your new engine, and have many fun and safe flying experiences with its use.

Safety Instruction and WARNINGS

Please read the instruction manual to become familiar with the features of the product before operating. Failure to operate the product correctly can result in damage to the product, and personal property and cause serious injury.

GT25 engine is NGH R&D manufacturing precision products. It must be operated with caution and common sense and requires some basic mechanical ability. This product is not intended for use by children without direct adult supervision. Don’t attempt disassembly, use with incompatible components or augment product in any way without the approval of our company. It is to read and follow all the instructions and warnings in the manual, prior to assembly, setup or use, in order to operate correctly and avoid damage or serious injury.

Age Recommendation:
RC engine is not a toy! Not for children under 15 years.

The engine is designed for use on a model radio control airplane. If it is used for any purpose, we cannot be responsible for its reliability of safety.

• NGH or their dealers aren’t responsible for any loss, injury or damage resulting from the misuse of RC engine.
• Keep away from the rotating propeller area while operating the engine.
• Do not wear loose clothing near the engine or the propeller.
• Do not operate the engine near loose material such as dirt, gravel, ropes, sand, etc.
• Always run your model engine in a well-ventilated area. Model engines produce possibly harmful carbon monoxide fumes.
• Always ensure that the propeller is securely attached to the engine shaft and all retaining fasteners are tightened properly before each flight.
• Always stand clear of and behind the propeller, and ensure the face and body are far away from the propeller blade after trajectory. Never allow anyone, to be in front of or to the sides of the propeller when starting or running the engine.
• Always ensure that small parts in the children can’t touch place to prevent children from swallowing parts;
• Always check the propeller nut tightening.
• Gasoline is extremely flammable. Be careful of any sparks from electrical contacts such as fuel pumps, battery chargers, etc.
• Allow your engine stop and cool before touching or fueling. The running engine of the surface temperature is high, easy to cause burns and another personal injuries.
• Be sure to check whether there are loose bolts before flying. When installing a muffler, the muffler in the threads of the screw into the engine exhaust, until the twist is fixed, it is recommended to use screw glue.
• Ensure the engine and muffler in the aircraft fairing environment with cold air, make sure the engine is cooling.

Product Specifications

Type： 2 Cycle Air Cooled Gasoline Engine（Only used for fixed-wing aircraft model）

Volume： 25cc| Bore： 33.2 mm
Stroke： 29 mm| Carburetor： Walbro WT978
Mix Output： 2.97HP@11000RPM| RPM Range ：1800-11000RPM
Ignition： NGH automatic advancing angle ignition      (RoHS and CE Certified； Rcexl Manufactured)
Ignition Power： DC 4.8V – 8.4V  1000mAH| Spark plug type ：1/4 – 32
Fuel: Standard 92 octane gasoline + FD 2-stroke oil| Mixing ratio： gasoline : oil = 25:1
Recommended propeller： 16×8, 16×10, 17×8, 17×10

（Two blades）

| Weight： engine 740g, ignition 100g, muffler 130g

Carburetor setup, adjust

NGH-GT25 two-stroke gasoline engine used Walbro WT978 carburetor is designed for NGH unique. It has the perfect stability of idle speed and acceleration sensitivity.
Always remove fuel from the carburetor after flight. Not doing so will result in rubber carburetor is components deteriorating over time, causing loss of engine performance.

Methods:
Start the engine without connecting the fuel pipe until we run out of fuel in the carburetor.

Setup Carburetor

1. Choke： Close it before the first start the engine, and quickly rotate the propeller, the fuel oil suction within the tank into the carburetor, when you start the engine should be open it.
2. The throttle control arm ： Infinitely adjustable-speed device, control the turning speed of the engine.
3. Nozzle： Connect the oil tank and supply the fuel to the engine.
4. High-speed needle.： After fully opening the throttle control arm ②, adjust the high-speed needle can get the best high speed.
5. Idling speed needle： Put ② return to the initial position, adjust the idling speed needle can obtain satisfactory low speed.
6. Idle mixture adjustment screw： Adjusting the fuel and air mixing ratio at idle, it actually controls the initial position of ②, adjusting ⑥ and ⑤ will obtain a better idling speed.

The initial setup of the carburetor is factory settings, the engine’s first start doesn’t need to adjust.

The factory setting status:

1. High-speed needle, Fully closed (clockwise) before exiting(anticlockwise) 1.5 ～ 1.75 times；
2. Idle speed needle, Fully closed (clockwise) before exiting(anticlockwise) 1.5 ～ 2 times；
3. Idle mixture adjustment screw, The throttle control arm at the other end of the limit pawl near the screw cone is about 1.5mm.

Adjust Carburetor:
When the engine running, you want to adjust the carburetor, please adjust it based on factory Settings:

In the process of adjusting the carburetor, please use a high-quality tachometer to determine the adjusted results, the tachometer you need to buy one. First adjust the high-speed needle: Engine run time will be turned on at full throttle position, adjust the high needle and watch the change of the tachometer, making the engine rpm reach the max per minute. Engine work in a stable high speed (please note: do not let the engine run boundary for a long time, this is big damage to the engine). Adjust the idle speed needle: The throttle return to the idle position, adjust the idle speed needle and watch the change of the tachometer. Let the engine run in a stable state of idle speed (Advice 16×10 wooden propeller idle speed at 1800rpm).

When necessary and idle mixture adjustment screw joint adjustments to ensure the engine idle speed stability, and smooth acceleration; If the engine is idling start difficult (Exclude CDI ignition power shortage, excessive fuel combustion chamber, spark plug problems, and so on). This shows that the air- fuel ratio (A/F) is low at idling, please adjust idle mixture adjustment screw, increase air ratio, or adjust the idling needle to reduce the amount of fuel, the A/F ratio achieves the appropriate proportion. ( Tip: The larger the engine propeller, the more perfect lower idle speed you will get. )

When the engine’s high speed and idle speed adjustment is completed, try to run the engine acceleration performance. First, let the engine to run 10 seconds at idling and then quickly move the throttle control arm at full throttle position, there will be the following three situations:

• Engine speed is responsive and smooth transition to the highest speed and instructions for the adjustment of the engine is very good.
• Engine acceleration has a cough performance, gradually transition to the highest speed, illustrate the idle speed needle set relatively rich oil, the idle speed needle to make a small adjustment (clockwise rotation), and then try again, try to accelerate the reaction constant adjustment until the engine reaches your request.
• Rapid throttle when the engine suddenly stopped running, this shows that the idle speed needle set relatively lean oil, the idle speed needle to make a small adjustment (anticlockwise rotation), and then try again, try to accelerate the reaction constant adjustment until the engine reaches your request.

Starting the engine

1. According to the engine connection method, install the engine on RC airplanes and lock the propellers. Made the carburetor initial setup and connect the spark plug, electronic ignition, and sensors put the fuel into the oil tank, and connect the power and radio control equipment.
2. Will the power of the electronic igniter at this time, make the carburetor inlet port in a fully closed position? Through the motor starter rapidly rotating propeller engine make the fuel in the tank inhalation of the carburetor, please pay attention to the suction of fuel should not be too much, otherwise will drown the spark plug, the engine start difficult.
3. Please open the carburetor throttle air inlet, power on the electronic igniter, then start the engine using the motor starter, the engine will begin to work, the fans will adjust the carburetor according to your own need. According to the above steps to adjust the carburetor adjustment.

Warning:
Make sure all bystanders, especially children, at least 30 feet away from the rotating engine.

Engine Break-in:
Please use high-quality synthetic oils, gasoline and machine oil’s mixing ratio is 35:1. NGH is recommended to use smaller size propellers at first break-in and follow-up about 10 times in flight. Keep medium speed running for 15 minutes (no more than 4000rpm) after starting the engine, then high speed running (6500 rpm) for 3 minutes, again medium speed running for 5 minutes, high speed running for 3 minutes, reciprocating 3-5 times complete break-in. Breaking in the engine carefully will increase its life. Please make sure the engine got the complete break-in before you use the larger load propeller.

Engine cooling:
If your engine is installed in the fairing, there must be air entering to cool the engine and ensure enough air flowing in the faring. Reference data: Outlet area should be 3-5 times than the entrance area to ensure adequate cooling.

Engine Failure Removal:
If the engine is difficult to start, idle speed and high speed unstable. Please check: whether the electric circuit and oil line of the engine is trouble, whether the engine leaks air, whether the electronic ignition works or its power supply is adequate, and whether the spark plug flame out. If necessary, replace it with a new spark plug.

Engine Maintenance

To reduce fuel consumption, and extend the engine’s life, please adjust the engine’s highest speed and make the engine run in an output maximum speed of 90% once the gas pedal is fully open. If the load is large (The propeller’s diameter and screw pitch are big ), the fuel must be adequate. If the load is small, the speed will be high while the fuel consumption will be less; Please make sure to empty the carburetor after each flight, otherwise, it’ll cause the rubber of the carburetor aging to affect the engine performance; Please clean the carbon deposition on the spark plug and keep the gap from 0.4mm to 0.5mm between the electrodes; If it’s difficult to start the engine, idle speed unstable or when high-speed operation flameout, please replace the spark plugs; Please clean the engine surface after used each time, it can make the engine get better cooling; The carburetor may be blocked seriously if you use different brands or types of lubricating oil together, you need select a better fuel filter; If the engine low-speed work for a long time, can lead to spark plug carbon deposition; Regularly check the fuel system, make sure do not leak fuel, do not leak air.

Engine Guarantee

If the NGH engine has performance defects caused by the defects of process, material and manufacturing, we certify that: Change for free within one year and Guarantee within two years since the date you purchased. Please note the guarantee is only for the original purchaser, not including Normal wear for the engine; damage caused by the failure of maintenance; damage for engine over speed operation caused by using a small propeller; Bearing rust; Crash; Use inappropriate fuel; Damage caused by foreign bodies; Damage caused by the unreasonable installation or operating environment; Damage caused by improper dismantle; Damage caused by any modification.

The instructions are only for reference and are subject to change without notice.

• Web: www.nghengine.com
• E-mail: ngh@ncdmoly.com
• xhlgjywb@163.com
• Skype: blue-sky-tan.

GT25 GAS Engine Exploded Parts View

(20x37x9)

04| 25110| 1|
05| 6302| 1| 6000.2RS

(10x26x8)

06| 6601| 1| 2.5×3.7×10
07| 25150| 1| COMBINATION
08| 17104| 1|
09| 6232| 1| 5/16″-24
10| 25120| 1| COMBINATION
11| 25141-Z| 1| COMBINATION
12| 25143| 1|
13| 25136| 1|
14| 25137| 1|
15| 25142| 1|
16| 25108| 1|
17| 25102| 1|
18| 6108| 6| M4x16
19| 25107| 1|
20| 25103| 1|
21| 6107| 4| M4x10
22| 7303| 2| 4.1×6.5×0.5
NO| PART| QTY| DESCRIPTION
---|---|---|---
23| 5002| |
24| 17221| | 3x5x50
25| 17216| 2|
26| 25200| 1| WT664A-102
27| 6116| 2| M5x40
28| 25406| 1|
29| 25400| 1| SUBASSEMBLY
29-1| 25401| 1|
29-2| 25403| 1|
29-3| 7309| 1| 30×0.9
29-4| 25402| 1|
29-5| 25405| |
29-6| 7303| | 4.1×6.5×0.5
29-7| 6212| 2| M4
29-8| 6401| 2| 4
29-9| 6221| | M4
30| 6109| | M4x50
31| 9201| 1| 1/4″-32
32| 9103| | A-01
33| 9104| | M3x5
34| 9202| | A-01
35| 17217| |

References

• Changsha Guanghua Aviation Technology Co., Ltd._Electronic electrician

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