Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 250Get this manual
6Rotate each piston ring so end of ring is aligned with locating pin as shown7Install Piston Ring Compressor8Remove screws and connecting rod cap from piston rod assembly being installed 9Coat cylinder bore with 2-cycle oilMatch piston assembly with cylinder it was removed from, and position piston as described belowPush piston into cylinder
IMPORTANT: Piston must be correctly installed and positioned as shownPistons marked with the word "UP" and with the letter "P" or "S" on top of pistonPistons with the letter "P" must be installed in the port side of engine and the word "UP" facing toward top of enginePistons with the letter"S" must be installed in the starboard side of engine and the word "UP" toward top of engine
aPiston Ring Compressor (91-823237)