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●Since a gas-engine has narrow range of air-fuel ratio, adjustment of the needles is severer than a glow-engine.
●The carburetor for the gasoline engine is the assembly of very strict and delicate parts. Make sure to use filtered
gasoline.
●Do not disassemble the carb by yourself. If you need to clean up the carb or there's any troubles regarding carb,
please consult the shop which you bought the engine from before disassembling.
Fig.9
Main Needle
CW→Lean
CCW→Rich
CCW→Rich
CW→Lean
7. Preparation for engine start
●Mount the engine on a robust and parallelized test bench or on the plane. (Either way, the engine should be fixed and
immobile.)
●Check whether the throttle can be fully closed and opened certainly.
●Check whether each code of the ignition system is connected certainly.
●Use about 1000cc tank for the test bench, or a tank which has appropriate capacity for the plane.
●Fill up the tank with the fuel mixture of gasoline : oil = 15 20 : 1 .
●Attach a well balanced D21 x P10
●To start with an electric starter, attach a spinner to the end of the shaft.
●To see the peak condition clearly, use a tachometer. It will prevent over-throttling or overheat. You can also use the
digital tachometer (Option).
●To check discharge from the breather, attach a gasoline-proof transparent tube to the breather nipple.
8. Break-in
●As Break-in is an important procedure not only to pull out the maximum performance of the engine, but also to
prevent the engine from overheat in the early stage of operation, it must be cautiously done.
●The purpose of break-in is initial lubrication and adjusting of the mobile parts under the condition of rich fuel mixture.
●Never make the fuel mixture lean during Break-in. It could cause seizure even during idling or low speed running.
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●Be sure to turn off the switch of the ignition system until just before trying to start up the engine.
●After turning on the transmitter switch, turn on the receiver switch.
●Check if the throttle and other servos move properly.
●Open the main needle about 2 turns from full close.
●Power on the ignition system.
●Open the throttle about 1/4 from full close.
●Starting with excessively opened throttle is dangerous since the plane jumps forward.
●Apply the electric starter to the prop and activate for about 5-10 seconds to start the engine.
●If the engine doesn t start up, open the main needle 1 turn more and apply the starter again.
●Once the engine starts run it for about 10 sec in low speed.
●Open the throttle fully and open the main needle until the speed drops just before engine stops. (Ref. Under approx
4,000rpm at full throttle.)
●If the fuel mixture doesn t become rich and speed doesn t decrease, open the slow needle too.
●Then continue running for 2 tanks under the same condition.
●During this initial operation, contact of each part inside the engine will be matched. So make the fuel mixture as rich
as the engine doesn t stop. Do not care about running smoothness at this step.
●Refill the tank and start up the engine again.
●Open the throttle fully and turn the main needle to achieve peak and less speed (richer) alternately about 5 times.
●Maintain the peak condition long gradually.
●When the peak gets stable, operate the throttle to vary from slow to high speed several times to check the response.
●After that run it for 2-3 minutes keeping high speed.
●When it comes to run smoothly at peak, break-in on the ground is completed.
●Fly it for about 20 times in rich condition to complete break-in in the air.
●After break-in, please run the engine in slightly rich condition as long as it doesn t affect to the flight.
●Tighten up the whole screws and adjust the tappet gap as discussed later.
9. Needle adjustment
●Before adjust the needles please set both needles as the standard values.
●In principle, the carburetor should first achieve peak by adjusting the main needle.
Slow （Idle) Needle
(Adjust with ⊖screw driver)
CW→Lean
CCW→Rich
Throttle lever
D23 x P8 prop to the engine shaft.
- 4 -
Standard values for the needles
For Main needle ：
1+1/6 1+1/2 turns open from full close
For Slow needle ：
Approx. 6 7 turns open from full close
(Then throttle should be fully closed)
Slow
Actually the best condition of the needles
varies depending on the prop, temperature,
humidity and so on.
Please adjust seeing the engine performance
High
during flight.
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