1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 176Get this manual
POWERHEAD
Pistons
IMPORTANT: If engine was submerged while engine was running, piston andor connecting rod may be bentIf piston pin is bent, piston must be replacedIf piston pin is bent, connecting rod must be checked for straightness1Inspect pistons for scoring and excessive piston skirt wear2Check tightness of piston ring locating pinsLocating pins must be tight
3Thoroughly clean pistonsCarefully remove carbon deposits from pistons, with soft wire brush or carbon removal solutionDo not burr or round off machined edges of ring grovesInspect piston ring grooves for wear and carbon accumulationIf necessary, scrape carbon from piston ring groovesRefer to procedure following for cleaning piston ring groovesCLEANING PISTON RING GROOVES Keystone (tapered) ring grooves
CAUTION