Right now my motor is 10.5 to 1 c/r with 95cc cylinder heads, and I can't find the paper work on the pistons(forged trw dome tops), but I was possibly going to run a cylinder head w/ 75cc and was curious if anybody could estimate what the c/r would move up to ? I know that without the piston specs that is a difficult thing to do but I was just looking for a guess or opinion. Also what is the formula to figuring out compression ratio ? Thanks.