Cycle News - Archive Issues - 1980's

I_~ression: 1984 Can-A_ 560 Sonic Rulebending boomer By Kit Palmer Photos by David Edwards Let's be realistic: There is no way a fourstroke can be competitive in today's Openclass horsepower wars against the proven two-stroke engines - that's been almost a rule for the past 10 years. Yet, aren't rules meant to be broken? Well, the new Can-Am 560 Sonic four-stroke should be 16 suspended from motocross tracks for breaking nearly all the rules. Since that's impossible, it's the competition that suffers. The Sonic is definitely a competitive piece of Openclass artillery, but does that mean .the big gun from Can-Am can actually win the hard-fought battles on the track? Last year Can-Am introduced it's 500cc four-stroke to 50-50 success. Although it wasn't the greatest bigbore machine on the market, it was the best strictly motocross-intended thumper ever to hit the showroom floors. But there was a catch. The 500cc Sonic had it easy - no competition. Noothermanufaetureroffered a motocross four-stroke, just enduro bikes that had tQ be stripped down and have gobs of money poured into the motor to make them somewhat competitive. Even if the others had built a motocrosser, the Sonic would . have been tough to beat. This year it is a different story. Husqvarna came up with an Open-class thumper of their own - the TCITX/TE Series. We evaluated theTX510 late last year and were very impressed with the machine, we wondered if the Sonic could maintain its head tart in the four-stroke motocross games? In the pi ts the 560 Sonic is an eye catcher with its Pepsident-white plastic tank and fenders underneath bright red and black decals. However, it won't keep its good looks for long. After a few weeks, the tank decal will blister, the stripes on the fenders will tear after a few crashes, and the remainder will then have to be removed to retain some of its dignity. The flashy stripes on the airbox look like they will last much longer, howeveI;. The Sonic is made "all over the world." It's Rotax motor is built in Austria while some of the other parts (Metzeler tires and Magura controls) come from Germany and Holland is repre ented with a White Power shock. Even a hint of Japan is carried on the bike with a Mikuni carburetor and a Nippondenso ignition. All these parts gather in Britain where the Sonic is assembled by Armstrong, not in Canada where they used to be. These parts are some of the best in the business so Can-Am doesn't fool around when it comes to quality. Throughout our impression, we experienced no mechanical problems. One of the biggest pluses in the Sonic's favor is the way it starts amazingly easy, even compared to a two-stroke, and a 250cc at that. Usually one kick got the thumper to fire up; hot or cold. That helps out a lot when you're stuck on the side of a steep hill in the middle of the desert, or stalled near the end of a long motocross race. You don't have to use every ounce of strength left in your body to kick it over, either. The procedure is very easy. First, there is a compression release lever on the cylinder head of the motor that you flick forward and locks automatically. Then you move the kickstaner through its arc with your hand until the little "window" in the side of the head turns white and the lever returns back to its original position by itself. This means the 560 is ready to be fired up. You can either stand alongside the bike or sit on top to kick it over; it really doesn't make much difference since it is so easy to tum over. When the Sonic ~ires to life, so will your eardrums. The Sonic is loud too loud. The exhaust pipe, a straight megaphone, has absolUlely no silencing. In a race, one strategy you couldn't use is the "sneak and zap" method, because the rider in front of you heard you coming two laps ago. However, it is intimidating. An aftermarket silencer spark arrester is already in the works. For a big-bore thumper, the Sonic is fairly light: Can-Am claims the Sonic weighs 256 pounds dry, which is about 20 pounds less than Honda's XR500 but slightly heavier than Husky's TX51O. Being light for a thumper is great, but with the lightweight two-stroke Open classers coming out of Japan (averaging about 2~0 pounds), it really doesn't mean much. While the weight of four-strokers is going down, so is that of the Honda, Kawasaki, Suzuki and Yamaha twostrokers. On the track the Can-Am is quite a handful. It feels heavy and there is plenty of horsepower on tap with a twist of the wrist. On a dry, slick, hard-packed track, the Sonic has a few advantages over most two-strokes. While a two-stroke has a tendency to come on the pipe too abrubtly, causing the rear end to fishtail and sometimes forcing' you off your line, the Can-Am tracks much more predictably when the throttle is wicked on. The Sonic's powerband is very smooth. It's best is down low and through mid range; great for the aforementioned slick track. But when there is an abundancy of traction, the Sonic would have a hard time against, say, the Honda CR500. And if the straight is long enough, the Honda . , I

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