The Wood-Rotax SJ600 Road Racer at Erico Motorsports

The Wood-Rotax SJ600 Road Racer at Erico Motorsports  Walk into Erico Motorsports on any given Tuesday and your eyeballs will naturally lock onto the gleaming European exotica and Italian rocket ships lined up like pieces of art on the showroom floor. But that's what Triumph, Ducati , Moto Guzzi, and Vespa want you to see. True gems, the machines with lived lives and bared souls - are scattered throughout the building like hidden treasures left by someone who actually really cares about two-wheeled history.

And ignore even those for a minute…

There are real prizes scattered even deeper amongst these gems, sitting quietly where they don’t need to explain themselves. These are the bikes that weren’t designed to impress anyone standing still.

And this is one of them. A Wood Rotax SJ600 with a history tied directly to Colorado racing and to Dr. Raymond Rossi, the man everyone called “Robodoc” when things went wrong at the track and help needed to arrive fast.

The Birth of the Supersingle Class 

To understand what made the Wood Rotax SJ600 such a weapon in the best possible way, you have to drop back into the late 80s, when American road racing was loud and proud, crowds roared, and everyone was increasingly obsessed with excess. Two stroke 250cc twins screamed their lungs out ripping up tracks and leaving trails of smoke. Four cylinder machines multiplied, grew heavier, and relied on technology to make up for what finesse used to handle. 

And then there was the Sound of Singles class.

This was where the contrarians went. Big bore, single cylinder race bikes that rejected the idea that more cylinders automatically meant more speed. They were brutal, mechanical, and honest but above all, they were light. A throwback to Grand Prix racing’s bare knuckle roots, but armed

with advanced suspension, serious chassis geometry, and engines tuned to hit the ground like a sledgehammer. 

The Ducati Supermono lived here. So did the Wood Rotax SJ600. These were not gentleman’s club racers or novelty sideshows. In the right hands, on the right track, they could and did humiliate far more complicated machines. The Sound of Singles wasn’t about nostalgia. It was about proving a point, loudly. 

Ron Wood: From Flat Track Legend to Road Racing Pioneer 

The Wood Rotax SJ600 Road Racer exists because Ron Wood never learned how to sit still. Designed alongside master fabricator Steve Jentges, the bike is the natural outcome of decades spent building machines that refused to lose. Wood’s reputation was already well established in flat track racing long before the SJ600 ever turned a wheel on pavement. 

In 1980, Wood officially retired. He sold his successful lighting-fixture manufacturing company, let his hair grow and turn white, kept the mustache, and promptly ignored the entire point of retirement. Within six months he had rented shop space in Costa Mesa, California, and went right back to what had consumed him since 1968: building dirt-track motorcycles that worked better than everyone else’s. 

His Norton-powered flat trackers dominated Friday nights at Ascot Park in the mid-1970s, hauling riders to AMA National podiums and establishing Wood as a builder who mastered the uncomfortable edge between control and chaos. These were not fragile race bikes. They were weapons in the right hands. 

When Can-Am, the motorcycle division of Bombardier, came calling with their new Rotax four-stroke single, Wood saw an opportunity. What began as engine development work quickly evolved into Wood Racing, a tiny operation that somehow became the third-largest American motorcycle manufacturer behind Harley-Davidson and ATK. 

The comparison was laughable on paper. Harley built tens of thousands of motorcycles a year. Wood Racing built fewer than 50. But volume was never the point. Every Wood-built machine was measured in precision, intent, and hand-crafted American ingenuity; Wood ensured that nothing needed the brute force of a hammer; every axle and pivot point was a buttery smooth piece of perfection. If mass production was about compromise, Wood was interested in the exact opposite

Engineering Excellence: The SJ600's DNA

Featuring a lightweight chromoly frame doubling as the oil tank and powered by a Rotax 676cc DOHC single, this machine was built for dominating the road racing scene, taking geometry cues from the Grand Prix racing RS250s and TZ250s of the day. At just 16 pounds, the frame is a quiet middle finger to the idea that steel had become obsolete. Built correctly, it proved that chromoly could be just as light, just as stiff, and arguably more honest than aluminum. This was not a theory. This was the proof. 

But Wood's innovation went further. Rather than running conventional oil lines from the engine to a separate tank, Wood used the frame tubes themselves as oil passages. The right downtube carries oil from the sump up to the tank (built into the frame as a massive reinforcement for the steering head), while the main frame tubes carry it back to the engine. The result? Just eight inches of oil lines instead of the typical six(ish) feet, and no need for an external oil cooler - the large frame area exposed to oil flow serves that purpose instead. 

Producing approximately 70 horsepower and weighing only about 260lbs, this bike was built to compete alongside the Ducati Supermono in the highly competitive Sound of Singles class. With its razor-sharp handling and impressive power-to-weight ratio, the SJ600 ran a 1:33.2 at Willow Springs - more than five seconds faster than any other single-cylinder machine, and competitive with many Formula II bikes of the era!

The Heart of the Machine

This particular bike is assembled like a hit list from the early 1990s GP racing scene. A full custom fabricated fiberglass fuel tank. Honda RS250 bodywork. Yamaha TZ250 forks. Tecnomagnesio wheels. No filler or fluff. No brand loyalty. Just the best parts a serious privateer could get their hands on when results actually mattered.

The Rotax engine began life in Can Am, ATK, and then KTM dirt bikes, but by the time it reached Wood Racing it was sharpened into something far more aggressive. Huge valves. A 44mm flatslide carburetor. Riders said it pulled like a strong well running 750, only with the unmistakable concussion of a fully committed single cylinder. Every power pulse landed like a solid punch right to the gut.

Only about 16 of these machines were built starting in 1988. Each one was effectively a hand crafted Grand Prix weapon. This was Ron Wood at full focus, combining innovation, craftsmanship, and hard earned racing knowledge into something that feels less like a motorcycle and more like a declaration of intent.

Dr. Raymond Rossi "Robodoc":

This particular bike was owned and raced by local legend Dr. Raymond Rossi. Ray was a larger-than-life member of the Colorado motorcycle racing community, helping develop medical protocols in local racing organizations that would influence rider safety nationwide. His dedication extended beyond motorcycles. Ray also served for years as a Rodeo Doc when Pro Bull Riding competitions visited Denver, bringing his expertise in trauma medicine wherever athletes pushed the limits of human performance. 

AMA Superbike, the USGP, and ultimately Moto America were all benefactors of Dr. Rossi's tireless dedication to rider safety. His work helped establish standards that are still in use today, making racetracks safer for competitors at every level. This racebike speaks to Ray's reputation for both technical precision and his almost superhuman ability to be everywhere he was needed on race day.

From Mike Cunningham to the Rossi Family 

Before Dr. Rossi campaigned this machine, it belonged to Mike Cunningham, another respected name in Colorado racing circles. The bike competed and passed through Mike’s capable hands, adding to its racing history and maintaining the high standards Ron Wood had built into every component.

John Beldock recalls many racing battles against this very bike, first with Mike, and then later Ray at the controls as he competed on a series of his own 125gp bikes, back in the day.

And while we’re on the subject of old racing stories…

Mike Cunningham, Ray Rossi, and this Wood-Rotax road racer actually share another very special place in John’s heart.  The year was 1996 and John was competing on a Honda RS125 GP bike at the now infamous Steamboat Springs road course.  When a downed rider’s motorcycle slid across the track and hit John exiting a blind corner, he was thrown, quite literally, hundreds of feet through a ditch alongside Mt Werner Road.  Being unconscious and hidden by hay bales, the trackside medical crew could not easily locate him.  Ray, actually competing in this race, stopped, turned around upon the red flag, and rode this bike back up the track to help locate the downed rider.  John recalls, “the first face I saw when my eyes opened was Mike Cunningham’s and the second face was Ray’s. They were working hand in hand alongside track staff offering medical assistance and then helped load John into the waiting ambulance bound for the Route County Medical Center.

We sadly lost Dr. Rossi in 2022.  Today, his Wood-Rotax racer is owned by Shelby Rossi, Dr. Ray’s daughter, ensuring that his legacy continues.  The bike has been made track-worthy and is on display at Erico Motorsports in Ray's former race livery - those distinctive colors that announced his presence at tracks across the region.

The SJ600's Racing Pedigree 

Wood saw an opportunity where others saw limitations. His dirt-track customer base was shrinking as American flat track racing contracted through the 1980s, and he kept fielding inquiries from road racers who wanted to adapt his frames for pavement. Rather than force a square peg into a round hole, Wood decided to design a purpose-built road racer from the ground up. 

His target customer was specific: a weekend warrior with a real job and real money, someone “grown up” who could afford quality equipment and wanted to race without becoming a full-time wrench. The typical SJ600 buyer stood around 5'11", weighed 165 pounds, and planned to hit the track a dozen times per season. They wanted the visceral thrill of a big single without the constant maintenance headaches of a two-stroke or the intimidating speed of a true superbike. Wood built them exactly what they needed, and then discovered he'd built something even better.

The bike's baptism by fire came at Daytona in 1987. With flat track ace Chris Carr aboard and running a detuned 500cc engine to meet Formula II rules, the hastily-finished prototype, completed barely a week before the green flag, showed flashes of brilliance despite lacking outright top speed. Give it time, though, and the SJ600 revealed its true character. Once Wood dialed in the suspension and unleashed the full 600cc mill, the bike became a Singles-class giant-killer, taking class victories while running lap times that embarrassed plenty of high-strung 250cc two-strokes. 

Steve Jentges: The "SJ" in SJ600

The "SJ" designation pays tribute to Steve Jentges, Ron Wood's chief fabricator and the man whose artistry in metal made the SJ600 possible. Jentges' credentials reached back to Indy-car chassis work in the 1960s, and in the 1970s he became known as the "J" in C&J frames - the very frames that had supported Wood's dirt-track Nortons. 

Slight and quiet, Jentges sparkled with enthusiasm when presented with something new to make. In just three days, he built the original aluminum gas tank from sheet metal - a masterpiece of compound curves and invisible seams. His welding produced the loveliest joints imaginable, and his perfectionism meant that engine and swingarm-pivot bolts would slide into their very-close-tolerance holes unforced. For every part he made, he built simple fixtures and jigs so that the next iteration could be not just as good, but better.

Visit This Legend at Erico Motorsports

Today, this Wood-Rotax SJ600 sits inside Erico Motorsports in Denver, close enough to study, close enough to feel. It stands as evidence from a time when innovation wasn’t filtered through committees and craftsmanship wasn’t outsourced. These were machines built by people who trusted their instincts and lived with the consequences. 

Whether you come at it as a vintage racing devotee, a big bore single fanatic, or simply someone who appreciates mechanical honesty, this bike offers a clear window into a brief, volatile moment in American road racing. It carries Ron Wood’s engineering stubbornness, Steve Jentges’ fabrication precision, and Dr. Raymond Rossi’s unwavering commitment to keeping riders alive when things went wrong. 

Come see this special piece of road racing history, and the rest of John’s vintage collection, at Erico Motorsports. Each bike here has earned its place. The Wood Rotax SJ600 isn’t a decoration or a nostalgia piece. It’s proof that a small Southern California shop, armed with skill, nerve, and zero interest in compromise, could build a machine capable of standing shoulder to shoulder with factory efforts and not blinking. 

About Us 

Located in Denver's vibrant RiNo District, Erico Motorsports is more than just a dealership - we're a community hub for motorcycle enthusiasts. Whether you're looking for your next bike, need expert service, or just want to admire some of the finest vintage machines ever built, our doors are always open. Stop by and experience the passion that drives everything we do. 

Visit us at 2855 Walnut Street, Denver, CO 80205, or call (303) 308-1811 to learn more about our vintage collection and current inventory.