If there is a noticeable "ring ridge" at the top of the cylinders, a ridge reamer must be used to machine it away before trying to remove the pistons. Otherwise, the top piston ring will hang up on the wear ridge and probably break a ring land on a piston, making the piston worthless. If there's a noticeable ridge at the top, the cylinders are probably worn too far to accept a re-ring job, but the ridge needs to be removed before disassembly anyway.
Jerry
