Sj600

SJ600

CYCLE WORLD TRACK TEST

Twisting the throttle on the fastest Single

ROCK-SOLID AND UNEXPECTEDLY FAST: THAT’S BEEN the consensus of every rider to swing a leg over the SJ600. And never, during this past year of development, has the SJ prototype lacked riders. Dirt-tracker Chris Carr rode it at Daytona, Formula II competitor Andy Leisner club-raced it, and Cycle World tester and endurance ace Doug Toland ran it as a 500 at the Laguna Seca and Sears Point Nationals. Editor (and vintage Singles racer) Paul Dean sampled the SJ during a test session, as did Superbike terror Doug Polen. Battle of the Twins rider Fred Eiker recently set single-cylinder lap records on the SJ600 at Willow Springs. I even got in on the act, racing the SJ on Mexican highways in La Carrera, where it carried me to a Singles-class win and fifth place overall.

While the bike evolved considerably over the past year, all of us who rode it encountered some constants. The SJ600 has always been small and low. The seat height, at 29.3 inches, falls two. inches below that of most streetgoing sportbikes, and the pegs are high. There’s enough room for a six-footer to tuck in, but anyone taller would have to consider relocating the seat. Those who fit will find the seat and gas-tank shape perfect; you can mold yourself into the bike without any interfering surfaces. Sitting on the SJ, you notice also that it feels exceptionally light; weighing 100 pounds less than a Yamaha SRX6Û0, it should.

Like most roadrace machines, the SJ has to be bumpstarted, a task that requires a rider and at least one pusher. Once lit, the SJ booms as only a barely muffled Thumper can, turning heads in the pits. Those heads stay turned as the SJ charges through the gears considerably harder than a production 600cc Four. With its large-valve, 44mm-carbureted, 600cc engine, Doug Toland compares it to “a good-running 750 or better, except the SJ600 feels like it’s going faster.”

Unquestionably, the big Rotax Single pulls hard from 6000 rpm, with an extra kick at 7000 that lasts past 8500. There’s a solid hammering to the individual power pulses that’s unique to highly tuned Singles or Twins; the engine feels much like that of a 750cc Ducati Montjuich V-Twin.

Whether or not the SJ vibrates depends upon who you ask, and their standards of comparison. Doug Polen, riding the SJ after a day on 600cc Fours, thought it shook like San Francisco in 1906. But the Rotax engine does use a counterbalance^ and Fred Eiker, experienced in racing Nortons and Ducatis, finds it amazingly smooth. I wouldn’t go that far, having lost feeling in my left hand after an hour spent running the SJ between 8000 and 8500 rpm at La Carrera. But the high-rpm buzzing in the handlebar and almost-padded seat normally isn’t debilitating, and won’t be noticed under most track conditions.

The SJ may vibrate less than legendary Singles, but it continues their tradition of outstanding handling. Thanks to a forward weight distribution and a very stiff frame, the SJ600 has exceptional straight-line stability, especially for a 260-pound motorcycle. The only time the SJ comes close to a front-end twitch is when cresting a bumpy turn over a hill, circumstances that can upset any motorcycle. But even if a bump kicks the SJ’s front wheel sideways, any wobble is completely damped in a single oscillation.

Stability hasn’t been purchased with turning ability, either. The SJ, with a 17-inch front wheel, steers moderately quickly, and can be flicked into corners hard. It holds its line well while still being able to change that line with small steering inputs. It inspires confidence; Fred Eiker goes so far as to describe the SJ600 “as the most ridable bike I’ve ever raced.” Doug Toland concurs: “In the highspeed corners at Laguna Seca it worked really well—it lets you go as fast as you can go.”

That ridability wasn’t always reflected in the bike’s suspension. Perhaps the area of greatest development, the SJ's rear suspension has worked well only within the last few months, without chatter in ripply corners. With the linkage-style monoshock and proper shock damping, the SJ works like a typical racebike: It rides firmly without harshness, and works better the harder you ride. Like most Formula bikes, the connection between rider and track is very direct: The thin seat padding gives more feedback than any streetbike pilot is accustommed to getting.

Other connections between rider and bike are similarly direct. Wood has made a study of throttles, and could easily write a monograph explaining the requirements for smooth throttle action on a big Single. He’s achieved it on the SJ, as well as good, if slightly heavy, clutch actuation and very controllable brake-lever feel. Shifting requires special mention, being as smooth, light and precise as on an exceptional 125cc motocrosser; several riders called the SJ the best-shifting machine they had ever ridden.

All in all, the SJ600 is an impressive motorcycle to ride, as well as simply admire. It reflects 20 years of Ron Wood’s experience, and he is proud of the results. “This roadracer is the best thing I’ve ever done.” he says. And he’s right. —Steve Anderson