1989 Ski-Doo Repair Manual, Page 248Get this manual
Section 03 TRANSMISSION Sub-section 02 (DRIVE BELT)
NOTE: To ease belt removal and installation on models using two Allen screws in driven pulley hub, tighten one of the screws using mm Allen wrench until drive belt can be slipped out of pulleySlip slackened belt over the top edge of the sliding half(TYPICAL)
NOTE: On Models using driven pulley with two Allen screws in driven pulley hubThe top of the drive belt must be flush with the driven pulley edgeScrew or unscrew each Allen screw equally to obtain proper belt positionTurn Allen screws 14 turn at time, then rotate driven pulley to allow drive belt to settle in pulleyCheck again, repeat as required