well unless it is the carb inlet size, i know i have gotten maximum power from this engine and the figures above are the maximum output i have gotten, the engine leaned out and ran smooth and at it's strongest at those rpms. so i don't think (without going to a larger carb) that i can get any more power than that from this engine. so i think it definitely needs a ring, and then maybe it needs a carb rebuild kit. that is just my opinion though, i don't think that more air and fuel is going to cure this engine from it's slouch.. that is if this engine is supposed to have more power than it is showing, or maybe you guys with other 30cc engines just have other brands that are better engines?? it either needs a new ring to increase the compression to make it turn an 18" prop effectively or it just will not turn one...?