1986 Ski-Doo Factory Shop Manual, Page 366Get this manual
Section 04 ELECTRICAL Sub-section 02 (IGNITION TIMING)
503 engine type: Look through the fanano check if the flywheel and the crankcase marks align503 TYPE
(TYPICAL1
Advanced timing
turn armature plate clOCkwise
MII?004001
If flywheel mark lor reference one previously scribed) align with center mark on crankcase (except on 503 type which has an arrow on crankcase), timing is correct
NOTE: All engines except 503 type: Center mark shows idea pOSitionOther marks show tolera nee range of 2
If timing adjustment is required, mwmd starter and starter