1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 195Get this manual
1Install piston ring in appropriate groove on piston using Piston Ring xpander ToolSpre ad rings just enough to slip over piston2C heck piston rings to be sure they fit fre ely in grooveLubricate rings and cylinder wall with 2-cycle oil 4R emove connecting rod cap from connecting rod being installed5Install ach piston with "Uidentification facing flywhe el endPistons MU be installed in this directionUP
52680Piston Ring xpander Tool (PN 91-24697)