1970-1973 Ski-Doo Snowmobiles Technical Data Manual, Page 19Get this manual
1973 MODEL Specifications NORDIC
90 NORDIC Noof Cylinders Bore Stroke Displacement Compression Rado Carburetor (Tillotson) Starting Overall Length Overall Width Height Height wo Windshield Weight (lbs) Bearing Area Ground Pressure (p.s.i Track (width) StdGear Ratio Lighting Coil Output Headlamp (Watt) TailStop Light Spark Plug (Bosch) Spark Plug Gap Breaker Points Gap Tank Capacity- Imp-U.SGasoline GasOil Ratio Type 640ER Two 76mm 70mm 635.1cc 9:1 HD Electric 101" 3412" 46" 36 112" 495 1242 sq.in.398 lS" 1933 120 watt