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.”
We cannot locate a VIN stamp on the frame. It’s possible the frame has been powder coated, or that the original VIN plate has come off, but we cannot confirm.
There is no odometer, true mileage is unknown.
Maintenance:
In preparation for the listing, the seller had us perform a safety inspection. Our service department notes the following on their condition report:
Gas Tank Internal Condition: Plastic with minor internal debris
Engine Oil Level: Low
Engine Oil Quality: Dark (Age Unknown)
2T Oil Level: Premix
Coolant Level: N/A
Coolant Quality: N/A
Front Hydraulic Fluid Level: Ok
Front Hydraulic Fluid Quality: Fail (>3% of moisture contamination)
Rear Hydraulic Fluid Level: Ok
Rear Hydraulic Fluid Quality: Fail (>3% of moisture contamination)
Clutch Hydraulic Fluid Level: N/A
Clutch Hydraulic Fluid Quality: N/A
Final Drive Condition: Dirty
Headlight High Beam: N/A
Headlight Low Beam: N/A
Passing Light: N/A
Parking Light: N/A
Turn Signals: N/A
Tail Light: N/A
Brake Light (Front Switch): N/A
Brake Light (Rear Switch): N/A
Plate Light: N/A
Horn: N/A
Kill Switch: Ok
Brake Pad % Remaining Front: 75%
Brake Pad % Remaining Rear: 80%
Forks: Leaking
Shock/s: Leaking
Tire Date Code Front: 19/13
Tire Date Code Rear: 29/07
Tire % Remaining Front: 90% Cracking
Tire % Remaining Rear: 90% Cracking
Tire Press. Front: 28 PSI
Tire Press. Rear: 30 PSI
Battery Standing Voltage: N/A
Charging Voltage @ 4k RPM: N/A
Running Condition: Runs Ok Not Well on Bench
Test Ride Completed: None Taken
Test Ride Distance: N/A
Notes:
-Rear Rim has been repaired
-Leaks Fuel
Recommendation:
-Carburetor rebuild
-Petcock Rebuild
-Hydro 2
-Possible Rebuild
-Air Filter Replacement
-Oil Change
-Front and Rear Tires
-Front and Rear Tubes
-Fork Rebuild
-Shock Rebuild
-Chain Replacement
-Tank Flush
Modifications:
We believe that this ATK is stock.
Inside of the tank:
It is riding on Dunlop Geomax MX51FA and Michelin with date codes of 2907 and 1913.
Cosmetic Blemishes: please see the album in the “Photos” tab for all known cosmetic blemishes. Here is a selection:
Currently located in Panorama City, California, (please make an appointment for an inspection) this ATK is offered on a Bill of Sale only. Have any ATK stories or questions about this listing? Let us know in the “Comments” tab!
