1972 Sno Jet Thunder Jet: Thetford Fiberglass Industries built their first 25 Sno Jet sleds in October, 1964. By 1970, Sno Jet was into racing with the GT I-II-III series with the GT III using a 793cc Hirth Honker motor.
In 1971, an advanced development team headed by Chief Engineer, Don Aho, developed the 1971 Thunderjet. The original Thunderjet had many innovative features such as a low engine placement, aluminum chassis, Sno Jet clutching and utilized the Yamaha 440R free-air motor. However, the machine was heavy and unstable. By 1972, Don Aho, with the help of a young racer from Michigan named Jim Adema, made the '72 Thunderjets much lighter and more stable. 100 each of 4 models were produced for racing. They were the 295cc, 340cc, 440cc, and 650cc models.
To say the '72 Thunderjets were successful would be a big understatement. They took over the race circuits. In Jan. of '72, Jim Adema lapped the entire field in one race at the Karwatha Cup in Peterborough, Canada and won the Canadian Cup on points. At Eagle River in '72, Thunderjets won the 800cc Cross Country and ruled the ovals with wins in the 295cc, 340cc, 440cc, and 650cc classes. The engine placement in the '72 Thunderjets was to influence the design of all snowmobile design going forward.
Thunderjets were produced in 1973 for the 295cc, 340cc, 440cc, and 650cc Mod classes. In 1974, the Thunderjet was produced as a SX-340-45hp model. In 1975, the last year for Thunderjets, they were all 440cc models.
Top of the Lake Snowmobile Museum
P.O. Box 2
Naubinway, MI 49762
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