March 5, 2011
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Dear MXA,
    My father tells me that when he was younger he raced an American-made motocross bike at a British motocross about 15 or 20 years ago. He couldn’t remember the name of it, but insisted that it was made in California, worked really well and that it wasn’t an ATK. Can you tell me what it could be?

There is only one possibility. There was only one American motocross bike that was sold in England. It was originally called the PBH, but was marketed as the Scott. It was powered by a Rotax four-stroke engine. It didn’t last long in England, but was later sold in the USA as the ADB Avenger. As you said, it was not an ATK?but it really was. ATK designer Horst Leitner, who built ATK motorcycles in Laguna Beach, California, was contracted to build a four-stroke prototype for a British firm. It was an typically unique bike from the pen of designer Leitner. The hanger/perimeter frame only had three main tubes attached to the oil tank/steering head. The shock was mounted horizontally above the left side of the swingarm. Engine oil was in the frame. The rear brake was on the countershaft (instead of the rear wheel to lower unsprung weight). Chain torque was reduced by an AMP system. Chain adjustment was via a snail cam. Horst built several bikes, which were tested by British racer Vic Allen, and Horst eventually shipped the tooling to England. The Scott didn’t last long, but is still around in America as the ADB Avenger. You can learn more about them at

This later American version has a lower frame cradle, but shows the unique rear suspension design. The gas cap was mounted at an angle to allow the gas tank to fit as low over the frame as possible.

The ADB Avenger.

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