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ATK 604

WHAT THEYSAID

"Many people whohave ridden the ATK 250consider it the finesthandling machinethey've ever thrown a legover. Light weight,phenomenal suspension, a great geometryand a tractable motorhave a way of winningyou over."

DIRT BIKE,December '87

"Out of the crate, youcan race an ATK 604and not feel outclassedby anthing on twowheels—two or fourstroke. Riding the ATK islike getting a head start.A big one."

MOTOCROSSACTION, April '86

ATK 604: DREAMMACHINE

For years off-road ridershave been wishing for apowerful, lightweight, wellsuspended and competitivefour-stroke machine. The ATK604 is the answer to theirprayers. Constructed inAmerica by the best frame artists the 604 is meticulouslydesigned to not only beat theother four-strokes, but todestroy two-strokes. Imaginea reliable 604cc, 60 horsepower thumper engine, cradled between Dutch-madeWhite Power upside downforks and shocks and hittingthe scales at under 250pounds.

Scientific motocross testshave proved that the ATK 604can out accelerate, out jumpand turn better lap times than

Rotax 604 four-stroke

If you could design yourown motorcycle you wouldn'tcompromise any aspect. Youwouldn't build a run-of-the-mill machine. You'd do itright! There are only 200 ATK604's built every year, andeveryone is built right fromthe ground up. The standardcomponents on the 604 arethe parts that other brands

elusive innovations that havemade ATK the leader in off-road technology-countershaftrear disc to lessen unsprungweight and improve brakefeel, Anti Chain TorqueEliminator to remove the harshness out of the suspensionand the famous side-mountedmaintenance free rear shock.

Chain torque eliminator

the best two-strokes, and itsbeen proven everywhere fromthe Carlsbad Grand Prix toBarstow to Vegas.

just dream about using—Super Trapp, White Power,Mikuni, Rotax, Magura andPirelli. Not to mention the ex-

Four-stroke lovers know thaithe ATK 604 is a breakthroughmachine. Isn't it time that youbroke through to the best!

ATK 250/406: IMPROVING THE LEGEND

In the world of motorcyling,nothing stands still, andtechnology often outstripsdesigns. Off-road motorcycleshave gotten better, buthaven't taken the rider intoconsideration in the rush fortechno-hype. Instead ofanother complicated shocklinkage, nightmare of plumbing or gummed-up powervalve the ATK design teamtried to build a new breed oftwo-stroke off-road machines.For ATK that means easier towork on, better handling,lighter than anything madeand free from the confines ofJapanese one-upmanship. Inthe ATK 250 and 406 two-stroke powered lightweightswe tried to design a machinethat was easy to work on, andthe result was a strong,reliable and simple air-cooledRotax powerplant. Famousfor their horsepower Rotaxengines are reknown for their

stone reliability. Water-coolingcomplicates other machines,increases complexity, lessensoverall reliability and adds additional fragile hoses, fittingand mounts. ATK's air-cooledengines can easily produce

Countershaft disc brake

the same amount of powerwith a lot less hassles on thetrail and in the garage.

ATK handling has been ravedabout by every test rider inthe world, not to mentionmagazine tests. Now imaginethat superb handling on abike that weights only 205pounds (the 406 weighs aneven more incredible 215pounds). ATK two-strokes areso light they float over bumpsthat other machines plow afurrow through.

Technology is our friendwhen used for good, but instead of designing more complicated things that do thesame thing, ATK featuressimpler innovations to dothings in a unique way. Looking for the airfilter? It's upand out of the way in the

gastank. Where's the rearbrake? It's tucked out ofharm's way on the countershaft. How big is thatgastank? Bigger than anyavailable production tank andslimmer and narrow at thesame time. Why is the gascap on the side of the tank?To make it easier to pour andsee gas in the tank. Why isn'tthe shock in the center of theframe? Because it doesn'tneed to be, and if it was you'dhave to be a contortionist toremove it.

Air filter and snorkel

ATK believes in buildingtechnically advanced two-strokes, but not at the expense of building a great off-road motorcycle. Be free!Ride an ATK!

ATK- Forthe rider whodemandssomething truly unique!

SPECIFICATIONSENGINE

FRONTSUSPENSION

REAR SUSPENSION

COUNTERSHAFT DISC BRAKE

WEIGHT

AIR FILTER

ATK 250/406The Rotax 250 and 406 two-strokes engines are

modern powerplants built in Rotax's Austrian factory. Utilizing an advanced slim-line rotary-valveinduction the 250 six-speed produces a broad anduseable powerband. The Open class 406 enginehas the latesty case-reed intake system and produces power so useable that it can be raced inevents as varied as motocross, desert racing, harescrambles, enduros or trail riding with nothingmore than a change of numbers.

Dutch Made White Power upside down forks arethe choice of the two of the three 1987 WorldMotocross Champions. The large diameter forksprovide an accurate, smooth and comtrolled ride.Each White Power unit is revalved to ATK specs toguarantee that they are tuned to Americanconditions.

Every year the Japanese manufacturers changetheir bikes' shock linkage and rising rate to the extent that in many cases this year's suspension isthe same one they had three years ago. ATK's innovative side-mounted White Power shock has theperfect shock curve and rising rate for optimumperformance. There is no confusing linkages orbell cranks to mess with, just super rearsuspension.

Rear brakes shouldn't be on the rear wheel.The disc brake mechanism adds to the unsprungweight, is vulnerable and creates serious torqueproblems with the rear suspension (known as rearwheel hop). ATK pioneered the countershaft discbrake which stops better, lessens unsprungweight and allows the rear suspension to workeven when the brakes are applied. No one elsecan make these claims, but they wish they could.

Weight is the enemy of suspension andhorsepower, and the less your bike weighs theeasier it is to get the most out of it. The ATK 250weighs an incredible 205 (dry). Some 125's weighmore than that! At 215 pounds the ATK 406 isalmost 20 pounds lighter than its nearest openbike competitor.

Why is the airfilter always wedged in under theseat where it interferes with the shock, chain andframe? Why? We don't know because theATK250/406 air filter is tucked up into the gastank.It is out of the way of water, mud, roosts, dirty airand the working parts of the bike. It makes somuch sense that other designs are senseless.

ATK 604Four-stroke engines produces the best, tor-

quiest and most useable power on the planet, andthe king of thumpers is the Rotax 604. This four-valve, 604cc, high compression racing engine isthe motor of choice of racing teams all over theworld. It's domination of the U.S. Four-Stroke National Motocross Championships has enhancedits imagine as a world class performer. Lightclutch feel, excellent five-speed shifting and areliability record that is unsurpassed guaranteesthe ATK 604 owner years of trouble free riding.

A four-stroke needs a strong set of forks to tamethe massive power pulses that are emitted fromthe Rotax mill. Upside down forks are the onlychoice for world class thumpers because of the increased rigidity, fork overlap and cartridge-styledamping. White Power 4054 forks grace the ATK604.

How good is the ATK 604's rear suspension?When the Honda factory team made an assault onthe National Four-Stroke Championship theymade an identical copy of the ATK frame, suspension and all. No suspension system made worksas well, with as few moving parts. Add our incredible dual swingarm, sealed bearings that insurefluid movement and no-binding at any speed andyou have the best suspension known to man.

Why mount the disc on the countershaft?Because the countershaft spins five times fasterthan the real wheel mounted disc, and as thepads are pressed against the faster spinning discbraking control and feel are increased because ofthe increased swept area. Additionally thecountershaft disc slows the motorcycle withoutlocking up the rear suspension because of opposing torque on the spring. And because it makessense.

Four-stroke motorcycles have always beenheavy. That's the price you pay to get thatbeautiful thumper power. But on the ATK 604 yousave as much as 30 pounds over the competition.At 246 pounds (dry) the ATK 604 is the lightestproduction four-stroke made. You can feel thedifference.

ATK built an airbox for the 604 that is so simpleit boggles the mind. The high position of theMikuni flat slide carb allows to the use of a specialK&N high flow air filter. The airbox itself is designed to use the seat base as part of the structure and the result is the lightest air filter/box unitever produced on a production motorcycle.

WOODSMEN POWER PRODUCTSHONDA CAN-AM

Randy Lewis619 - 3rd Ave. East

Alexandria, MN 56308 -I723 LAGUNA CANYON ROAD, LAGUNA BEACH, CALIFORNIA 92651 • (714)497-7525