When you first get your new RC nitro engine, the piston and sleeve are a very tight fit. Unlike normal engines, the RC Nitro 2-stoke uses a tapered sleeve for compression, while a normal car would use piston rings. What you need to do is run the nitro engine very gently for a while, so that the piston and sleeve can work together and find the perfect fit.

As with everything in this hobby opinions vary depending on who you ask, I'll share with you the methods I use top break-in my new engines. It's always best to refer to the manual for your engine, and follow the manufacturers instructions for RC engine break-in, if your not sure always choose the longer break in method.

The first step is to find the right settings for your high and low speed needle, these you can find in your manual. If you have no idea that a good place to start is 3 turns out for the high speed and 1 1/2 for the low speed needle. If your wrong with this these settings then your nitro RC car won't even start.

The 5 Tank Method

First you need to Start Your Nitro Engine.

Let it idle for a full tank of fuel. This lets the engine get up to temperature and ensures that there are no tiny defects in the piston and sleeve, if there are they will be worn smooth during this process. Your RC Nitro engine must be very rich, unburnt oil and fuel must be comming out of your exhaust, this serves two purposes.

1. It keeps the engine lubricated
2. It will wash out all the tiny bits of metal that will come off during the break in period
3. Once the tank is done let the car cool down, I normally use a little after run oil at this point, I'll remove the glow plug, add a couple of drops of after run oil and turn the engine over a couple of times, then replace the glow plug

Do small figures of 8 at about 10-25% throttle. It's important to break-in your nitro engine under similar conditions to how you plan to use it. The engine must have some load on it when it's breaking in, in this case doing figure-8's will but a very small amount of load on the engine. It's important to vary the throttle when you do this, but don't rev it past 25% throttle.

Repeat the above step for your third tank of fuel, please note that your tune is still extremely rich and the car should want to stall a lot, if it does stall, lean the high speed needle by 1/8th and continue.

Now it's time to start leaning your Nitro RC Engine. What you need to do is repeat the process from tank 2 and 3, but bring the car back every couple of minutes and lean the engine by 1/8th of a turn. Be careful not to lean it out too much, there should always be a healthy amount of smoke coming from the exhaust. You should also see a lot of oil and unburnt nitro fuel being dumped on the road, this is very healthy for the engine, but tends to destroy your glow plug. The Glow plug you use during break-in will most likely not be good for racing.

During the 4th tank you can start to increase your revs, never hold the throttle open for more than 2 seconds, best practise is to drive around at low throttle and every so often hold the throttle open for a couple of seconds.

Carry on as your were with the 4th Tank, keep leaning it out and letting the engine rev higher. By now your RC Car's Nitro Engine is almost ready for a proper run. If your unsure you can repeat this process with as many as ten tank of nitro fuel, increasingly leaning out the engine and increasing the revs.

Never keep your engine at full revs for more than a few seconds during the break in process, this can seriously shorten it's life. It's important to break the engine in using similar revs that you would use while racing, if you don't rev the engine to it's maximum range it won't perform to it's maximum potential.

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