1983 Ski-Doo Shop Manual, Page 201Get this manual
SECTION 04 ELECTRICAL SUB-SECTION 02 (IGNITION TIMING)
ELECTRONIC IGNITION SYSTEMSNIPPONDENSO
277 ENGINE TYPE
Two methods are detailed in this section, the first using Top dead center gauge, the second using stroboscopic timing light4Rotate the crankshaft by the fan counter-clockwise until the piston is at:Up to serial number 3,376,857 INDIRECT TIMING: 2.85 mm (0.112") B.T.D .C- Serial number 3,376,858above INDIRECT TIMING: 2.6 mm (0.102") B.T.D.CDIRECT TIMING2.3 mm (0 .090") B.T.D .CBTDCBefore top dead centerAt this point, the crankcase mark and the fan outer circumference mark MUST align
Top dead center gauge verification
1Disconnect spark plug wire and remove spark plug2Remove the cylinder cowl and hold the hood in an open position3Install and adjust T.D .Cgauge on engine as follows: Rotate magneto clockwise until piston is just before top dead center With gauge in adaptor, adjust roller so that it is parallel with dial faceTighten roller lock nut
!TYPICAL)
Adaptor lock nut Adaptor