FORGOTTEN MOTOCROSS TECH: THE SNOWMOBILE ROOTS OF AUTOMATIC MOTOCROSS BIKES

Rokon is still in business today selling its iconic two-wheel-drive Trail Breaker model at www.rokon.com.

Motocross history is filled with examples of creative ideas that were heralded as groundbreaking, but, because of the rapid rate of change in development, sank into the swamp of forgotten technology. Although some are best left abandoned, others were truly innovative (if not ultimately successful). MXA loves to reveal motocross’ tech trivia. Do you remember this idea? The torque converter Rokon 340 MX.

Racers have always dreamed of automatic transmission motocross bikes. Today, we are closer to that reality than ever with point-and-shoot electric-powered bikes, but, back in the day, the automatic dream was hard to fulfill. The most famous automatic motocross bike was the Rokon 340MX (only produced in 1975-’76). It was powered by a 335cc, Sachs, two-stroke snowmobile engine. The Rokon utilized a Salisbury torque converter for a truly automatic transmission. The torque converter allowed the engine to run between 6000 and 6700 rpm most of the time. The most famous Rokon motocross racer was Florida’s “Rokon Don” Kudalski. He won several races for the Rhode Island company, including the Open class at the 1976 St. Petersburg, Florida Inter-AMA. Bob Harris, Ron Bishop, Dave Mungenast and Jim Hollander were also major players in Rokon’s short history in off-road racing.

The 335cc Rotax snowmobile engine was fired up with a pull rope. It wasn’t as easy as it sounds.

Riding a Rokon 340MX was unique, since the torque converter didn’t provide any engine braking. Rokon’s cure was to mount touchy KH disc brakes (eight years before any of the other manufacturers). Although you didn’t have to shift the 340MX, you had to deal with the bulging belt and pulley gears that made the Rokon incredibly wide. Plus, since it was a snowmobile engine, you started it with a lawnmower-style pull rope.

The front and rear brakes used solid undrilled rotors. There was no shift lever or clutch lever. The rear brake pedal faced backwards.

MXA’s Jody Weisel raced a 1976 Rokon 340MX Cobra. He says, “You didn’t have to shift, just wick it up and hang on. It made strange noises as the belt slid up and down the cone-shaped pulley gears. It was fast and even faster when you chopped the throttle because it freewheeled. The first time I grabbed the solid rotor disc brakes at the end of a fast straight, I was catapulted like a Guernsey cow from a French trebuchet. I landed with 275 pounds of Rhode Island-built snow blower on top of me.”

 

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