1980 Ski-Doo Shop Manual, Page 263Get this manual
SECTION 05 SUB-SECTION 05 (PULLEY ALIGNMENT)
DISTANCE ADJUSTMENT (except Citation and Mirage)
To obtain maximum vehicle performance, adjust pulley distance as follows: Adjust pulley distance to nominal distance(Refer to Technical Data)2Install new drive belt on vehiclePrior to final adjustmentthe drive belt must have break-in period time of one to two minutes3The final adjustment of pulley distance should be performed by using the belt deflection method as follows: