I agree with fourstroke, though I think saying running it 4-stroke rich "will inevitably ruin your engine" is a bit harsh. I won't ruin the engine at all. It will open up the piston/liner fit and result in a loss of a bit of RPM, maybe as much as 1.5k, but probibly less. For sport flying, you'll never notice. However, you did say you want to race the engine, so you want to avoid it.

As a side note, when you start the engine, run it up to full power promptly. Let it run at full power for a couple of sedonds, then back off to idle. Don't start it and go right to idle. You need the piston and liner to warm up quickly, running for extended periods at idle, or idleing when cold has the same effect as extended 4-stroking on the motor.