Break-In Procedure for TRX Pro.15 Engine

Note: Traxxas carburetors are preset from the factory using an airflow meter. Do not readjust your carburetor settings, before breaking in the engine, unless you suspect they have been changed. To learn more about your carburetor settings, click here.

PLEASE READ THESE IMPORTANT NOTES BEFORE YOU BEGIN:

Proper engine break-in is critical to achieving the fastest, most-reliable engine performance. Allow yourself about 1 to 1 1/2 hours to break in the engine. The break-in time is not the time to impress your friends with your new model. You must wait until the engine is fully broken in before attempting sustained high-speed runs.

DURING BREAK IN...

During break-in, it is crucial that the engine be set rich. Even though the needles are preset at the factory, slight adjustments to the factory settings may be needed depending upon altitude (thinner air requires a leaner mixture), temperature, fuel used, etc.

How do I know if the engine is rich enough?

To determine if your engine is set rich enough for break-in, you should look for the following conditions:

• Heavy, blue exhaust smoke
• "Blubbery" engine sound
• Heavy bogging throttle response. The throttle response will not be crisp and abrupt.
• "4-stroking"- Normally, a two-stroke engine fires once for every two strokes of the piston. When the engine is "4-stroking", it is firing once for every four strokes of the piston. All of the unburned fuel carries away heat and any tiny metal particles.

During the break-in period, your engine may appear to malfunction with symptoms such as stalling, inconsistent performance, and fouled glow plugs. Don't give up on it! These are just "break-in pains" that every new engine has to go through. They will disappear once you get through the break-in period.

• Use fuel with the same percentage of nitro which you plan to run every day. Special break-in fuels are not required.
• Drive the model on a smooth hard surface.
• Run with the body off for extra engine cooling.
• Keep extra glow plugs handy. The break-in process can cause deposits to form on the glow plug, leading to failure.
• Do not allow the fuel tank to run completely empty. An extremely low fuel level causes the fuel mixture to be too lean.

THE FIRST TANK OF FUEL

Once the engine is started, drive the model slowly for the first few minutes to warm the engine. Drive the model on a flat paved surface in an oval configuration. This will cause you to naturally vary your speed over the entire RPM range. During this break in time ease in and out of the throttle slowly to avoid stalling the engine. The goal is to simply keep it running. Do not run at full speed during the first tank of fuel. Do not rev the engine with the wheels off the ground. High, no-load RPMs can damage the engine.

The fuel mixture setting may require slight adjustment to correct for different altitudes and temperature. Just make sure the engine is running rich (high volume of fuel flowing through the engine) look for the following conditions:

1) The engine should accelerate sluggishly
2) There should be a thick trail of blue smoke coming from the exhaust every time you accelerate out of a curve.
3) "Blubbery" engine sound

If you do not observe the conditions above, then turn the high speed needle out 15-degrees (counter-clockwise) and retest. Vary your speed between low and medium throttle until the first tank of fuel is almost empty. Stop the engine and allow it to cool for 5-10 minutes before proceeding.

TANKS TWO AND THREE

• Refuel the model.
• Turn the high-speed needle in 45-degrees (clockwise) (1/8 of a turn)
• Turn on the radio system. Press the primer button several times and restart the engine.
• Continue driving on your oval course, varying your throttle, until the second tank of fuel is used up.
• Run two tanks of fuel through the engine at this setting.
• Allow the engine to cool 5-10 minutes between tanks.

Important: Be sure to allow the engine to cool between each run.

TANKS FOUR AND FIVE

• Refuel the model.
• Turn the high-speed needle in 45-degrees (clockwise) (1/8 of a turn)
• Turn on the radio system. Press the primer button several times and restart the engine.
• Continue driving on your oval course, varying your throttle, until the fourth tank of fuel is used up.
• Once again, run two tanks of fuel through the engine at this setting.
• Allow the engine to cool 5-10 minutes between tanks.

After the fifth tank of fuel, the engine break-in process should be complete. Now, click here to learn how to tune the engine for maximum power.