1978 Ski-Doo Shop Manual, Page 225Get this manual
SECTION 04 SUB-SECTION 04, (IGNITION TIMING) (8Hold centrifugal lever in full advance position (toward magneto rim) and rotate crankshaft until P.T.Opiston approaches T.D.CAs soon as same specified piston position before top dead center as on magside is reached the timing light should fluctuate or tone signal level varyIf necessary to adjust proceed as follows:
6Slacken the two (2) armature plate retaining screws and turn timing instrument ONRotate magneto counter-clockwise until specified piston position before top dead center is reachedEngine type Direct measurement B.T.D.CIndirect measurement B.T.D.C
With centrifugal lever in full advance position and piston at specified position, slacken lower breaker points set retaining screw then readjust breaker points gap until fluctuates or tone signal level varies If timing is too early decrease breaker points gap toward lower limit, i.e0.35 mm L014"), then recheck timing If timing is too late increase breaker points gap toward upper limit, i.e0.45 mm L018"), the recheck timing