One more thing, make sure that you are using the right fuel. Everyone I know around here is running 30% heli in their YS's. I never tried it but I understand that YS engines run badly on 15% or lower nitro fuels. And I also understand that fuels with low oil content or castor in them can cause all sorts of problems. So 15% Omega, Coolpower and the like are not at all appropriate.

Walt