1978 Ski-Doo Shop Manual, Page 114Get this manual
SECTION 04 SUB-SECTION 02 (ENGINES)
CLEANING
Discard all gasketsClean all metal components in non-ferrous metal cleanerScrape off carbon formation from cylinder exhaust port, cylinder head and piston dome using wooden spatula
NOTE: Once the circlips are installed turn each circlip so the circlip break is not directly on piston notchRemove any burrs on piston caused through circlip installation with very fine emery clothO
NOTE: The letters" AUS" (over an arrow on the piston dome) must be visible after cleaning
Circlip break