How to Mix Nitro Fuel

Create a baseline to work with for your fuel mixture. Begin with a fairly even fuel mix for basic engine performance by opening the low-speed needle on your engine one full turn clockwise and the high-speed needle two full clockwise turns. For new engines, use this mixture to break in the vehicle before performance tuning.

Break in your RC car to basic performance levels by running it through five tanks of fuel--three tanks at idle and two tanks at 1/4 speed. The break-in period ensures that the engine runs well without any unexpected expansion of the alloys of the metal interfering with performance mixing. It also extends the life of your engine at best speeds by hundreds of hours.

Adjust the needles to change the amount of air and fuel added to the nitro mix. Adjust the low-speed needle to control the amount of fuel used in the mix. Adjust the high-speed needle to adjust the amount of air. Turn clockwise to increase the feed from the needle and counterclockwise to decrease the feed.

Place your vehicle onto a box, so that the wheels do not touch the ground but the mixing needs on the engine remain accessible.

Set the vehicle throttle on full to rev the engine at its top speed. Watch the vehicle for smoke emission and listen for the pitch of the engine. An excess amount of smoke combined with low engine sounds means there's too much fuel in the mix. Open the high-speed needle clockwise up to two turns to lean the fuel mixture, increasing the amount of air in the fuel-to-air ratio. Check for a lessening of smoke and a rise in engine pitch. Stop turning the needle when the pitch steadies out with little smoke blowing from the engine exhaust.

Run the engine through an entire tank of fuel at the present fuel mix. If the engine continues to run with a steady pitch, then the mix is correct. If the engine stops, then there's not enough fuel present in the mix, and you need to turn the low-speed needle open a full turn to increase the amount of fuel running through the system.

Test the fuel adjustments to ensure sufficient flow by pinching the fuel line leading to the carburetor so that the fuel stops during engine operation. With correct flow, the engine will run for two or three seconds before gaining in speed and then dying. If the engine runs longer than the three-second period, lower the fuel amount in the system by turning the low-speed needle back about 1/16 turn at a time. If the engine dies immediately, add about 1/8 turn of the needle until you reach the desired time interval.

Lean the mix again using the high-speed needle after adding fuel to the mix. This will allow you to accommodate the new level of fuel.

Test various mixes until you have the engine running at a steady high pitch with little smoke and until you have the ability to maintain that performance level through an entire tank of fuel.