1978 Ski-Doo Shop Manual, Page 224Get this manual
SECTION 04 SUB-SECTION 04, (IGNITION TIMING)
TDC GAUGE PROCEDURE
1Disconnect spark plug wires and remove spark plugs2Remove rewind starter assembly from engine then remove the fan protector, starting pulley and "V" belt
With gauge in adaptor, adjust roller so that it is parallel with dial faceTighten roller lock nut
t- Outer 'ring set screw