ATK560
CYCLE WORLD RIDING IMPRESSION
JUST LIKE CHEATING
RON LAWSON
TAKE MY ADVICE: NEVER ASK A racer what he thinks of four-stroke motocross bikes. Chances are you'll get either a "you're-not-serious-are-you?"stare, or an hour's worth of propaganda straight from The Ministry of Thumpers. Everyone's glad to offer an opinion, but separating myth and counter-myth from the truth can be a full-time job.
You might. for instance, be told that four-strokes put power on the ground with unbelievable traction: that they have great bottom-end torque: and that they have an excit ing. deep. throaty sound. You might also be told that four-strokes are so heavy and so slow that they couldn't spin the rear wheel on sheet-ice coy ered with STP: that the only reason the bottom-end power on four strokes seems decent is because they have so little top-end horsepower. And on top of that, they're loud.
In matters such as thi~, there's only one way to find out the real truth about four-stroke motocrossers, and that's to race one for yourself. So that's exactly what I did. Horst Leitner, owner of ATK, loaned me one of his hand-built, Ro taxpowered ATK 560s for CMC's FourStroke Championship at Perris Raceway. and by the time it was all over, few of those preconceptions had held up. Okay,, so the bike did have a deep, throaty sound; but, then, it was a rather loud, deep, throaty sound. In just about every other way, though, my ride on the ATK had shown both sides of the four-stroke myths to be little more than that: myths.
I showed up at the track Sunday morning, having raced at the same location the day before on a Honda CR500R. I knew the track, and I knew well how a two-stroke motocrosser could handle its jumps, berms and whoops. After riding the Honda, I was sure that racing the ATK was going to seem like riding a twowheeled equivalent of a cement truck. It would be okay, though; I'd be riding against other cement trucks.
Surprise Number One: As far as I could tell, the ATK got me to the first turn every bit as fast as the Honda had the day before. Against a back drop of TTs and XRs. that translated to the kind of holeshot that only hap pens in your very best dreams. So much for four-strokes not having much top-end. Surprise Number Two: The ATK had far less low-end power than the CR I had raced the day before. Where I would lug the CR through the turns with the throt tle just barely cracked open. I had to rev the big Rotax motor, and maybe even hit the clutch lever before the ATK would jump out of a turn. So much for four-strokes having torque.
The biggest surprise of all, though. was how efThrtlessly the bike cruised around the track. Leitner claims his bike weighs 246 pounds dry (about 1 5 pounds more than the average Open two-stroke). and I had no rea son to doubt him. Most big thumpers land from jumps like a Hefty bag filled with wet sand. But the ATK borders on being `~normal"-that is. it doesn't drive the footpegs through your feet and halfway up your shins every time you hit a bump. Make no mistake, the ATK is a big bike, but only when compared to the best two stokes of today. A few years ago it would have been considered agile, even by two-stroke standards. Then there's that sound. There's something about the feeling you get from revving a thumper that no twostroke can offer. When all that snarl ing and booming happens at your command, not only do you get the feeling that your bike has power. you get the feeling that you have power. I was enjoying thundering though my first moto so much that I nearly for got I was in a race. After all. I hadn't seen or heard another bike since the gate had dropped. It didn't occur to me that I couldiz `t hear any other bikes, not while I was sitting on top of the loudest noise-maker on the track. So I was just rumbling along in my own little thumper world when out of nowhere, a stock-looking Honda XR600R quietly slipped past me and into the lead. It was a classic sneak attack. I had the fastest, lightest. trickest bike on the track and had let a cement truck pass me.
He didn't stay in front long, though. Watching him swap and hop through the bumps made me believe every bad thing I had ever heard about four-strokes in motocross. When he finally bailed off on the last lap, I wasn’t surprised. I was amazed that he had stayed up that long.
Watching that XR rider made me appreciate the ATK’s suspension even more. During the first moto, the suspension worked superbly, although if I had to pick nits, the rear shock spring might have been a little soft. That would have been fine for me, but I was sharing the bike with Doug Dubach; he rode it in the Pro class and I rode with the Intermediates. Dubach was hitting all the bumps harder than I was, and between motos he asked if anything could be done to make the suspension a little stiffer. Leitner obliged by putting a stiffer spring on the rear shock and turning up the preload on the fork. I was more or less drafted into using the same setup.
As it turned out, the new shock spring had been installed with too much preload, and it was too stiff even for Dubach. I watched as he pounded into all the jumps in his second race, the rear suspension barely moving. He won anyway, but that just put more pressure on me. If he had been able to win against the Pros, what excuse would I have for not doing the same against a bunch of Intermediates?
I still pouted about the stiff spring before my second moto, and Leitner hastily tried to relieve some preload. With a few seconds to spare, I made it to the line and pulled another ATK holeshot—the bike’s fourth of the day, including Dubach’s set. My fears were for nothing, for the bike handled superbly. The front and rear suspension, although still stiff, worked well on the sharp bumps and impacts of Perris’ sandy track. My only complaint was with the gear ratios in the Rotax motor. First and second gear both were rather low, with a large jump to third. Since the bike had little low-end power, the gap between second and third seemed even wider than it actually was. Several days later, I had a chance to ride the bike with a different pipe, one tuned more for low-end power. That cured the low-speed stumble I had whined about during the race, but the bike still was a revver.
In truth, however, it really seems like a crime to complain about anything the bike did. After all, I had it a lot better than those poor saps on the XRs and TTs. I cruised to an even easier victory in the second moto, the madman on the Honda planting his face somewhere on the first lap and giving me a clear path all the way to the finish. In fact, it was almost too easy. Riding the ATK was obviously an advantage; I felt sort of like I had cheated.
That’sjust a little frustrating, too. I had gone into the race to clear up some myths about four-strokes, but as it turned out, I didn’t clear up anything at all, at least not about fourstrokes in general. I did, however, learn quite a lot about one particular thumper—the ATK. It’s competitive with anything.
And that’s no myth. S
