Engine break-in

Four Stroke Engine Carburetor

Four Stroke Engine Carburetor


How to Breaking-in the engine for nitro rc planes?


This process is very important to every new engine you purchase. All nitro engines benefit from essential care when they are run for the first few period of time – known as running –in or Break-in. As a nitro rc planes the process helps the internal parts to mate together within the load at operating temperature. 


Therefore, it is very important to complete the break-in before allowing the engine to run continuously at high speed. New engines from well known manufacturer are produced with modern and high standard materials, and need only a simple run-in period to carry out. This can be done either on the engine bench test or on the model itself.


The procedure is recommended as follows:


  • Apply the same fuel and prop as you intend to use with this engine.
  • Open the needle valve 3-3.5 turns from the fully closed position and start the engine.
  • Open the throttle slowly to the mid speed position, and disconnect the glowplug.
  • Now open the throttle slowly to the fully opened position and run the engine for no more than 5 seconds then, immediately slow the engine down by opening the needle valve approximately one turn. The rich mixture will cool the engine and provide enough lubrication at the same time.
  • Repeat this process, please be remembered to running the engine fast and slow by mean of needle valve while keeping the throttle fully open. Then begin to extend the short periods of high speed operation until two tanks of fuel have been finished.
  • It will be good idea if you try to repeat the same procedure for another one or two tank. This is not serious as you can use this engine for the first flight right away. In preparation for the first flight have the needle valve set on the rich side and adjust the throttle trim on the transmitter so that the engine does not stop when the throttle is closed to the idle setting.
  • With each successive flight, close the needle valve very slightly until it is set for full power at the end of about 10 flight. Do not “over-lean” the mixture in an attempt to extract more power before the breaking –in period.

If you suspect that the engine is slowing down during the flight (overheating possibility) reduce the power on your transmitter and land the aircraft to readjust the needle valve to a richer side. Have fun and successful flight with your nitro rc planes.       

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