How to Tune Model Engines
To maintain its top performance, model engines require occasional fine tuning and adjustment. Tuning the engine basically requires adjusting the ratios of air and fuel that are used in the engine mixture. More fuel in the mixture is considered richer and more air is considered leaner.
Materials Needed:
- Fuel tubing
- Tighten both the engine's high speed and low speed needle valves until they are closed fully. From the closed position, loosen the high speed valve to complete five turns.
- Slip fuel tubing that is a clean length onto the carburetor. To find the location of the carburetor look right next to the low speed valve.
- Open the carburetor just a little, about 1/5 of the way and gently blow into the tubing. As you blow into the tubing, slowly open the low speed valve. As soon as you hear air flowing into the carburetor, stop opening the low needle valve. Completely close the high speed valve.
- Open the rest of the carburetor 4/5 of the way and again blow into the tubing. As you blow this time, slowly open the high speed needle. Once a strong flow of air passes through the carburetor, stop opening the needle and pull off the carb tubing. Now you can reconnect the engine and turn it on.
- Raise the throttle completely and then adjust the high speed needle until you barely have any smoke and noise coming out. Once you get to this point, loosen the valve by 30 degrees.
- Reduce the throttle until the engine becomes idle. Allow the engine to idle for several minutes with no interruptions.
- Listen to the engine as you pinch the fuel line closed. Make the fuel richer if it speeds up and dies immediately by loosening the low needle valve. Make the fuel leaner by closing the needle if it takes longer than five or six seconds.