1989 Ski-Doo Repair Manual, Page 333Get this manual
Section 03 TRANSMISSION Sub-section 07 (CHAINCASE)
DRIVE CHAIN ADJUSTMENT
Replace O-ring on tensioner adjustment screwFully tighten tensioner adjustment screw by hand, then back off only far enough for hair pin to engage in locking holeThis initial adjustment should provide 3-5 mm (18-1364 in) free-play when measured at the outer circumference of the bra ke disk CAUTION: Free-play must not exceed mm (1364 in), re-adjust if necessaryWARNING: If the specified free-play is not reached with the tensioner screw fully tightened, re place chain and check the condition of sprockets