Atk

ATK

LITTLE CHANGES, BIG RESULTS

AMERICA'S ONLY OFF-ROAD motorcycle manufacturer, ATK, doesn't have any radical new models for `91. Rather, it has made numerous improvements to its motocross and enduro line of twoand four-stroke Singles.

The first change, and the most needed, is a new method of drive-chain adjustment. Adjusting the chain on previous models was often a nightmare, as the eccentric adjustment of the company’s unique chaintorque eliminator sprockets was so limited. Now, there are conventional axle adjusters in addition to the existing system. Problem cured.

Jetting the fiat-slide Mikuni TMX carburetor is easier now, too. A triple-taper needle eliminates the need for pilot-jet changes. The needle jets can't be changed in this carburetor, which also caused past problems due to a rather limited selection of needles. But a wider selection of the tapered needles should solve that, and the 250 and 406cc ATKs come standard with two extra needles, just in case.

ATK’s countershaft-mounted disc rear brake has had more than its share of brake-pad problems over the years—they often heated up and wore out rapidly. Carbon-metallic pads are said to eliminate these headaches and they should also improve the brake feel.

The two-strokes get different cylinder porting for a broader powerband. and a new head stay that reportedly reduces vibration by 50 percent. And additional packing in the two-stroke's silencers makes them quieter for '91.

Additional all-model improvements include a redesigned guard for the rear-brake rotor and a stronger chain guide. New graphics adorn front numberplates, seats and fork legs. A non-cartridge White Power fork and single WP shock are revalved to provide a plusher ride, and a cartridge WP fork is a S 1 50 option when ordering a new bike.

ATK's '91 updates should eliminate most of the complaints our test riders voiced about the 1990 bikes. We’ll let you know as soon as we get our hands on an ATK test bike.