1978 Ski-Doo Shop Manual, Page 160Get 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
Place clean cloth over crankcase to prevent
circlips from falling into crankcase then use pointed tool to remove circlips from pistonDrive the gudgeon pins in or out using suitable drive punch and hammer_ CAUTION: When tapping gudgeon pin in or out of piston, hold piston firmly in place to eliminate the possibilities of transmitting shock and pressure to the connecting rodAt assembly, place the pistons over the connecting rods with the letters AUS (over an arrow on the piston dome) facing direction of the exhaust port
NOTE: The letters "AUS" (over an arrow on the piston dome) must be visible after cleaning