1978 Ski-Doo Shop Manual, Page 222Get this manual
SECTION 04 SUB-SECTION 04, (IGNITION TIMING)
IGNITION TIMINGTWO CYLINDER ENGINES (248, 294, 305, 343, 346, 402, 440, 444, 640 TYPES)
FOREWORD
For timing purposes, it is necessary to separate the twin cylinder engines into two groups
NOTE: Breaker points gap can change upon tighteningAlways recheck after tightening
GROUP 1: 248, 294 engine types
These engines do not incorporate an automatic advance mechanismThe ignition timing marks on the magneto ring are stamped at the full advance position
4Disconnect junction block at engine then connect one lead of timing light (flashlight type) or of tone timer, to the blue wire (magside) leading from engineConnect other wire to fan cowl (ground)5Slacken the two (2) armature plate retaining screws and turn timing instrument ONRotate crankshaft until magside piston approaches top dead center and timing marks align (while holding centrifugal lever in the open position, toward magneto rim)Retarded
GROUP 2: 305, 343, 346, 402, 440, 444,