Those of us who were boating the late 70's and early 80's were using ABC OPS aero engines converted to marine use. One of the things a guy named Bill Trammel here in the Tulsa area did was "lap" his piston to the sleeve. It was done with 1000grit wet dry sand paper, and a lubricant, ie wd 40. When he finished the pop at the top was still there, but the feel of the compression was reduced a tad and a very smooth transition at the top was accomplished. He also did it to allow quicker breakin and use higher nito. I have done that some over the years with engines in fact just finished it on an MDS 40. Makes for a great feel at the top and the motors run like nothing else. It is a feel you get with time and experience. Mike the piston, cylinder first if it is REALLY tight, take your time, get the fit and believe me it will make a difference. Rpms will pick up too, and pipe response is better.

An old boater
Curt