Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 243Get this manual
POWERHEAD
CAUTION
Each connecting rod and end cap are matched machined set and must never be mismatched6Inspect pistons as outlined in "Cleaning and Inspection," following7Use Piston Ring Expander (91-24697) to remove piston ringsAlways install new piston rings
8Using an awl, scribe identification number of connecting rod on inside of piston (a)Reassemble piston on same connecting rod9Using tool (91-52952A1), remove piston pin lockrings from both ends of piston pinNever re-use piston pin lockrings