R/C Helicopter Hobby in Singapore

Article 1: How to tune a glow engine?

A Webra 52 AAR helicopter glow engine

(1)Carb (2)Crankcase (3)Piston (4)Backplate (5)Cooling head

If it is a new engine.....

A new engine should be run in properly so that all the moving parts can sit in securely. For OS engine, I usually run that engine in a rich setting for the first tank. How do I know if the engine is run in? When you turn the crankshaft with your hands, you should feel the smoothness of the moving parts.
After running in the engine, you have to tune the engine. From reading and learning from experienced fliers, there are 3 things you should look out for during engine tuning:temperature, power and smoke.
There are usually 2 needles on an engine. Some engines have 3 needles. The main needle, as the name suggest, is the bigger needle. For OS engine, it controls the fuel flow beyond idle point(20 to 100% throttle) For Webra engine, it controls the top end of the throttle(70-100%). The idle needle is small one, u need a minus screw driver in order to turn it. For OS engine, the idle needle only controls the idling of the engine(0-20%). For Webra engine, the idle needle control 0 to 70% of the throttle. OS engine is very popular in Singapore. The important thing is that the user must not touch the idle needle, which is set by factory. Tune the engine using the main needle. For OS engine, you can start from 2 turns from close. I will start the engine, and let the engine idle for 30 seconds. Then I touch the crankcase and feel the temperature. It will be cold. Throttle up the engine, which will most likely bod down because it is running rich. Throttle down and then turn in 3 clicks. Do this repeatively until the engine throttles up without bogging. Bring the heli to a hover, then give a full throttle climbout. Ask someone to help you if you can't do a climbout. The engine may bog at the top end, you have to listen to the sound. Now lean in the engine 2 clicks at a time until the engine doesn't bog. It is important to check the engine temperature periodically so that you will not over lean the engine, causing over heating. Overheating can kill the engine!!! How hot is hot? If you feel the crankcase, you should be able to leave your finger there for a few seconds until you withdraw in pain. Once you reach this point, the engine is more or less tune. You can richen(turn out) the main needle by 2 clicks so that the engine is a tiny bit rich. This will help to provide more lubricants to the moving parts.

An overheated TT39 engine, resulting in a broken piston.

If you have started tuning and have no idea where your idle and main needle are?

This instructions only apply for those who has messed up the idle and main needle settings. The idle needle is set in factory using special hydraulics method. DO NOT reset the idle needle unless you know what you are doing. If you have already reset the idle and don't know where is it now, you can try out these steps. First, close the idle and main needles completely by turning them in clockwise direction. Then open up the idle needle by 2 to 3 turns anti-clockwise and the main needle 4 turns anti-clockwise. Now try to start the engine. If the engine doesn's start, close the idle needle 1/8 of a turn until you can start the engine. Once the engine is started, let it run for 30 seconds. Then touch the crankcase with your finger. Remember the temperature, it should be cool. Then throttle up the engine. If the engine bogs and couldn't provide enough power for hovering, close the main needle 3 clicks anti-clockwise. Do this until the engine can provide enough power to hover the helicopter. Touch the crankcase and feel the temperature. It should be getting warmer now. Next, put your helicopter into a full throttle climbout. If the engine bogs, close the main needle by 3 clicks. Do this until you can get a decent full throttle climbout. Then check the crankcase temperature. If the temperature is too hot, open up the idle needle by 1/8 turn. Hopefully, the crankcase temperature can decrease so that the engine is not over heating.

Well, the procedure for tuning engine varies from place to place. This method doesn't work 100% of the time. If you have difficulties, you can contact me and we can meet up and I see what I can do.