2008 Polaris ATV Predator 50, Sportsman Outlaw 90 Service Manual, Page 53Get this manual
ENGINETRANSMISSION PistonRing Identification
The letters "IN" or the larger of two valve pockets on the piston face the intake side of the engine (UP)Other numbers may be used for size identificationGenerally, four stroke engine rings have rectangular profileThe numbers or letters on all rings must be positioned upwardUn-marked rings (such as oil control ring rails) are non directionalAlways see ring installation text for specific ring information
Engine Removal
123Clean the ATV and work area thoroughlyRemove seatRemove front cab and foot rests