Clean the varnish from piston skirts and pins with a cleaning solvent. DO NOT WIRE BRUSH ANY PART OF THE PISTON. Clean the ring grooves with a groove cleaner and make sure oil ring holes and slots are clean.
Inspect the piston for cracked ring lands, skirts or pin bosses, wavy or worn ring lands, scuffed or damaged skirts, corroded areas at top of the piston. Replace pistons that are damaged or show signs of excessive wear.
Inspect the grooves for nicks or burrs that might cause the rings to hang up.
Measure piston skirt (across center line of piston pin) and check clearance.
