I took the other cylinder off & the piston looked the same as the first. I used the B type piston with the A cylinder the last time it was rebuilt which was approx 2yrs ago.

How do you measure piston to bore clearence?

Could the excessive blow by be due to rich jetting? Would the excess oil in the mixture find it's way past the rings through time? I know the rings need to be replaced but they are not too far past the limit. I also noticed the limit is .65mm in the parts manual.

Thanks for the help.