In regard to the 2 stroke engines, Rotax has very good charts showing what jets and needles, ect should be used at standard tempatures and sea level. They also have charts telling how to adjust those jets for different tempatures and altitudes. I think one is best advised to make sure their jetting is correct according to the factory charts. Then if the prop is pitched for about 6250 static, EGT temps/plug color should be right. If EGT temps are still to high, you possibly have other problems such as leaking crankcase seals and such. Take care, Jim Chuk