1980 Ski-Doo Shop Manual, Page 157Get this manual
SECTION 03 SUB-SECTION 03, (IGNITION TIMING)
3Check air gap between magneto ring and trigger callThe gap should be 0.8 to 1.2 mm (.031 to .047")
If necessary to adjust: unscrew slightly the two (2) screws holding trigger coil bracketthen move bracket up or down
4Check timing using stroboscopIc timing light (on each cylinder)WARNING: Place ski tips against the wall, raise rear of vehicle so the track is not in contact with the ground and place it on stand equipped with protectorMake sure nobody passes behind the vehicle during timing procedureMagneto ring mark and crankcase central mark should align at 6500 RPM