1989 Ski-Doo Repair Manual, Page 42Get this manual
Section 02 ENGINE Sub-section 01 (247 ENGINE TYPE)- NOTE: The following procedures can be done without removing the engine from chassis
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
REMOVAL
(Without removing engine from chassis)
Remove the following then lift cylinder and cylinder head: console pulley guards spark plug air duct muffler, connecting tube and exhaust socket spark plug cable clamp from fan cowl primer hose from carburetor untighten rubber flange collar then move carburetor steering column bolt at upper column and spirol pin, washer and short tie rod from bottom end
NOTE: The letters "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