I just got a 2002 blaster but the top ends blown up and the cylinder wall has some gouges and scratches . I found a wiesco piston that's 68mm ( 2 mm bigger than stock ) . My dad can bore it over he said but doesn't know if to bore the cylinder 2 68mm or a hair bigger so it's not to tight and there's room for the piston rings to open up . Where should we bore the cylinder too ??