1980 Ski-Doo Shop Manual, Page 130Get this manual
SECTION 03 SUB-SECTION 02, (ENGINES)
CLEANING
Discard all gasketsClean all metal components in non-ferrous metal cleanerScrape off carbon formation from cylinder exhaust portcylinder head and piston dome using wooden spatula
NOTE: The letter AUS" (over an arrow on the piston dome) must be visible after cleaning
Clean the piston ring grooves with groove cleaner tool, or with piece of broken ring
Exhaust manifold