Go ahead and break the engine in. By what you are telling us it sounds ok. Break in the engine by the manufacturers instructions. I have one of these engines and after breakin you couldn't ask for a sweeter running engine. My air leak sealed off after using about a gallon or two of fuel with castor in it. The only thing that the air leak affects is the engine turning off. Thats all. Avoid idle bar glowplugs with this engine they mess up the throttle transition. OS A3, OS #8, and Tower Power Plug work best. Good luck.

Sport10