Basic Engine Break-in Procedures

Here are a few general tips for breaking in your engine. The "turns" on the needle valves are general settings. You should always look at the engine manufacturer's recommendations, but if they are not available, the below settings should get you started without damaging your engine.

The First Tank
Your first tank of fuel should be running the truck at a very rich high-speed needle valve setting. This allows the fuel to carry as much oil as possible into the engine to lubricate the internal parts during the break-in.

Open the needle valve 2-3/4 turns from fully closed (counterclockwise). When closing the high-speed needle, close the needle until you feel some resistance. DO NOT overtighten or you will damage the engine.
Start the engine.
Once the engine is started, open the high-speed needle valve around 1/8 turn at a time, finding the setting where the engine just barely runs. This may take a few times adjusting the needle, running the truck away from you and back, then adjusting the needle. The engine will perform sluggishly and stall from time to time - that is normal.
Run the vehicle back and forth at medium speeds, slowly accelerating and decelerating the truck.
After a minute or two of running, make sure the engine is not overheating by putting a drop of water on the cylinder head and watching it boil away. If it boils away immediately, stop the engine and allow it to cool. Open the high-speed needle around a 1/4 turn before starting again. This is a good habit to get into every time you run to ensure that the engine does not overheat during any run. Looking at the smoke that comes out the exhaust is also an indicator of how rich or lean the engine is running. If there is a good amount of smoke coming out of the exhaust, then chances are good that you are running rich.
Run the vehicle back and forth at a medium speed until the tank is almost out of fuel. Do not allow the tank to run out of fuel. This leans out the engine and can cause overheating.
Stop the engine and allow the engine to cool before the second tank. This normally takes around 10 minutes.

Tanks 2-5
Turn in the needle valve (clockwise) around 1/12 turn from the previous setting. Run the vehicle back and forth. You should notice that the engine will perform better during each run. Stop the vehicle periodically to check for overheating. If it is too hot, stop the engine. Wait for it to cool, then open up the needle valve and restart. After the 5th tank, you should be near to the peak performance of the engine.

These steps were based on recommendations and apply to any nitro engine. You should always look at the engine manufacturer's recommendations on needle valve settings before you began.