1986 Ski-Doo Factory Shop Manual, Page 258Get this manual
Section 03 TRANSMISSION Sub-section 03 (DRIVE PULLEY)
ADJUSTMENT
11, Shim (alignment)
Far pulley alignment procedure, refer to section 03-05
5, Shim (neutral)
For neutral adjustment, proceed as indicated belowWARNING: Shim(s) (5) is(are) used to obtain neutral function of the drive pulley when engine is idlingProceed as follows when retaining bolt is torqued: With new drive belt installedit should be possible to insert minimum of 0.80 mm (.030") thick feeler gauge on each side of the drive belt simultaneously pushing drive belt to sit on bearing