ok bottom line... you want to be in the low 200s for several tanks, and low rpms. at that point pull the plug and turn the flywheel... if you still feel squeaky metal pinch its got more breaking in to do. as long as you feel that squeaky/tight feeling with the plug out its not broken in. if you make the motor turn high rpms when its tight, its really hard on the con rod and itll stretch out the crank end and your off to a bad start.... thats what you want to avoid.[:'(]
so take it easy on the motor and dont rev it high, run as rich as possible until you feel the metal pinch go away. keep the temps in the low 200s untill then, once broken in keep it under 260ish... but an occasional 300 wont kill it, but its not good!

all motors seem to break in at different rates, so checking the pinch with the plug out is the best way to check.