1985 Ski-Doo snowmobile Service Manual, Page 346Get this manual
Section 04 ELECTRICAL Sub-section 02 (IGNITION TIMING)
WARNING: Place ski tips against wall, raise rear of vehicle on stand so that track does not contact the groundMake sure no one passes behind the vehicle while engine is runningKeep clear of track and other moving partsNOTE: Turn headlamp "on" when checking timing
Start engine and point timing light straight into inspection holeMag side spark plug
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Timing too advancedturn armature plate clock wise
To adjust remove rewind starter assembly and starter pulleyTiming light -::: pick up
Using mm Allen key, loosen the two armature plate retaining screws and lightly move plate in appropriate direction!Refer to the difference between timing marks to determine how much to move the armature plate)