1974 Ski-Doo Shop Manual, Page 129Get this manual
Two timing procedures are detailled in this section; the first using the timing marks stamped on the engine, and the second using T.D.Cgauge ENGINE TIMINGONE CYLINDER
PROCEDURE USING TIMING MARKS
1Disconnect spark plug wire and remove spark plug2Remove rewind starter assembly from engine then remove the starting pulley from magneto ring3Rotate crankshaft until breaker points, visible through magneto ring opening, are fully openAdjust points setting to .014".018" using feeler gauge and screwdriver as illustrated
6Rotate the magneto counter-clockwiseof turn and slowly turn the magneto back in clockwise directionAs soon as the timing marks align the breaker points should just begin to open and the timing light should fluctuate, or the tone signal should no longer be heard 7Check and adjust the edge gap as follows: From timing marks, rotate magneto clockwiseof turnHold advance mechanism centrifugal weight in the open position (toward magneto rim), then slowly turn magneto back counter-clockwise until timing light fluctuates or tone signal is no longer heard At this point, check the distance between pole shoe trailing edge and magnet (edge gap) with strip of cardboard of appropriate width (Refer to Technical Data Section) If the edge gap is less than specified, loosen armature plate retaining screw and rotate armature plate ass'y counter-clockwise until correct edge gap is obtained Reset the ignition timing and recheck the edge gap