Thanks guys for the opinions. I'm building a "KX 560" with a CR500 rod and 91mm piston. I had to move the cylinder up 5.5mm for the piston skirt to close the exhaust port at TDC. The head, combustion area, was milled out to copy a CR500's head, but the volume was only taken out to 52cc not 60cc like the CR500, because the water passages were getting close. So I held off on milling the cylinder in order to verify what the compression would be. And like I said above it only came to 110 lbs. Unfortunately I have finals this week and a hillclimb coming up so I'm scrambling trying to get this done in time! Afterwards I'll tear it down and have the cylinder milled down.