just wondering what kind of head your engine has, billit or with full top shroud?(sp). The reason I'm asking is that I've heard that the billits don't cool the cylinder as evenly as the full shroud does. I ran the billit before upping the motor to a 30.5cc and went through 3 top ends in a summer, the cylinder was scored badly but not the piston. It could have been dirt or not cooling properly but they were all scored in the same place.( Note: I was running at 40:1 but now I'm running 32:1 in the new engine)