2002 Ski-Doo Shop Manual Volume Three, Page 116Get this manual
Subsection 02
Section 04 ENGINE (377 AND 503 ENGINE TYPES)
Hold tool firmly against piston then strike on round end of tool with plastic hammerCirclip will move from tool groove to piston groove
420 876 171 1
A17C01A
A01C02A
1Piston notch 2Circlip break at o'clock
CAUTION: Circlips must not move freely in the groove after installationIf so, replace themNOTE: Be sure to restore the chamfer around all cylinder sleeve port openingsBefore inserting piston in cylinder no4, lubricate the cylinder with new injection oil or equivalentInstall proper ring compressor on piston assemblyENGINE TYPE 377 503 RING COMPRESSOR PN 420 876 090 420 876 970