1985 Ski-Doo snowmobile Service Manual, Page 344Get this manual
Section 04 ELECTRICAL Sub-section 02 (IGNITION TIMING)
377,447engine type: Look through inspection hole and check if the flywheel and magneto housing marks alignIf the marks do not correspond to the specificationscribe new mark on the flywheel
Start engine and point timing ligth straight in line with the timing marks:
377,447: Look through inspection hole503: Look through the fan377,447 models:
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503 engine type: Look through the fan and check if the flywheel and the crankcase marks alignIf the marks do not correspond to the specificationscribe new mark on the flywheelFan cover removed
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