Over on the auction site we’ve got one of the most interesting American-built dirt bikes of all time. ATK was founded by Horst Leitner, an Austrian motorcycle racer who came to the US in a quest to build his own bikes. In 1981, Leitner developed and patented what he called “Anti-Tension Kettenantrieb”, a device designed to eliminate chain torque. He took the acronym of that creation to name his new motorcycle company, which made a name for itself for creating some of the best 4-stroke dirt bikes you could buy.
ATK started by building kits powered by Honda XR engines, but they soon moved to using Rotax units. In their 1989 brochure, ATK was proud to show off that they were the fastest-growing motorcycle company in the world, having quadrupled their production in less than five years. “ATK is the only company in America producing off-road motorcycles. Why aren’t there more? We don’t know, but we do know that when we built a bike that suited the demands of serious riders, they beat a path to our door.”
That year they offered three models: the 250, 406, and 604. The 406 utilized an air-cooled 399cc single-cylinder engine that produced between 35-40 horsepower. Dry weight was 213 pounds.
ATK featured a “high and dry” airbox with the air filter tucked inside the curves of the gas tank and they took pride in their top tier components, with WP suspension front and rear (with hand-valved ATK internals), a chromoly frame made in the USA, and for 1989, a chromoly swingarm, as well.
One of the other notable features of the ATK was the rear brake, which was a disc on the countershaft. “Why isn’t the rear brake on the rear wheel? Because if it was, the rear wheel would weigh five pounds more than it has to, and every one of those pounds would have to go up and down with each bump on the track. Unsprung weight is the enemy of good suspension.”
This example has been sitting around for a few years on display and it starts but it will need some work before it gets ridden again. Still, it’s a cool example of a rare bike and I just love the swingarm setup. Find this ATK for sale in Panorama City, California with bidding up to $600 and the reserve not yet met here on Iconic Motorbike Auctions.