How to Tune a RC Gas Engine?

Tuning the gas engine for radio controlled planes will ensure proper acceleration and keep top speed without harm the engine. Here are some useful tips for tuning your gas engine. Once knowing the working principles, this work will become much easier.
To distinguish a gas engine is out of tune or not, at first you should know about the working procedures of carburetor and other settings.
Actually, professional players may tell the tuned engines from others easily by observing the cycle status of engines. Most two cycle engines are unable to do "four cycle" works. The way to make it sound like a four stroke engine is by forcing the sparkplug to intermittently miss.
Normally it's inadvisable, while two stroke engines do have enough space to set. This can start the engine much easier and it need little or no warm up time during cold temperature. Thus the plane will fly preferentially by taking this advantage. This way will cause problems like:
1. The low end needle on a carburetor is always the closest one to the engine; while the high end needle is the closest one to the intake.
2. There is no fuel adjustment for idle fuel, only air feed set by the idle stop or servo.
3. Both the two ends needles offer the top end fuel supply.
So we still need to tune the carburetor to ensure normal operation.
First, adjust the smaller screw on the carburetor for low-end acceleration and idle. Turn to the left to enrich the gas mixture or to the right to reduce the mixture.
Second, adjust the larger screws of the two to left and right respectively. Tune to the right is to make the mixture reduce and for more speed; to the left aims to get a richer mixture and cool the running temperature.
Then, tighten the exhaust and intake manifold screws to make the engine start easier and won't die after a few times of running.
At last, remove the air filter and tighten the two bolts inside that go through your engine. They can hold the motor together and avoid air leaks as it may cause dying of starting.