he phrase “parts-bin bike” isn’t a term of endearment. It has an edge to it, an easy dig. But when you’re a champion off-road racer with a box of extra parts from your championship-winning Kawasaki KX450F and you decide to turn those parts into a one-of-a-kind dirt-bike bobber, perhaps the phrase doesn’t seem so bad. “I started building it in 2012, which was the year that I won the WORCS championship,” says Taylor Robert, the professional racer and the mind behind this machine. While he’s since switched over to a factory ride with KTM, Robert was racing for Kawasaki when he snagged his first WORCS title. Along with the Team Green semi, a small army of race crew, and an endless flow of neon energy drinks, being a factory-supported rider meant there were always backup parts for putting broken machines back in fighting shape. So, while the actual championship bike from Robert’s 2012 season is currently sitting on a shelf in his kitchen, there were enough spare parts left over that an idea began to form.

Putting a dirt bike engine into a street-oriented chassis is nothing new, but what Robert had in mind was a ground-up custom skeleton, built around the beating heart of the machine that had loyally carried him to the top of so many podiums. Perhaps it was sentiment, a desire to have the motorcycle look and feel as important as it was in his memory, that made the project take Robert six years to complete. Or maybe—and this is probably a stretch—building a custom bike just always takes longer than you expect.

After wallowing in frame-design purgatory for half a decade, Robert took the rolling chassis to someone who would care about the project as much as he did: Jonny Wiseman, Robert's former race mechanic from those Team Green days. A skilled technician and suspension tuner, Wiseman has long since moved on from wrenching on factory machines and now runs The Ride Shop in Phoenix, Arizona. While he's as familiar as anyone with dialing in the performance of a KX450F, Wiseman had to enlist the help of fabricator Ian Waite to solve the long list of challenges that came with adapting a dirt bike to life on asphalt. So, for the bike, the rider, and the mechanic, this was an overdue reunion.

2012 Kawasaki KX450F
It has a very raw feeling to it, from the vibration of the engine to feeling the pavement through the hardtail.Spenser Robert

“It was a super-big pain in the ass,” says Wiseman, describing the trial-and-error build process. The 2012 KX450F was designed as a kick-start only, short-ratio, battery-free, headlight-free, motocross machine. Even the simplest modifications dictated additions, like a LiPo battery or wiring for a Rigid Industries headlight. Then there were the changes to the gearing and the effort of setting up the low-slung machine to feel dirt-bike familiar, with a GPR triple clamp and Renthal handlebar. Not to mention the cruiser configuration, which required cutting down the KYB fork to 4 inches of travel.

But that was the easy stuff. An elaborate Fox Shox linkage suspends the seat over the unforgiving hardtail chassis, and a custom FMF titanium/carbon system handles exhaust duties. A custom-built secondary fuel tank, gravity-fed by the carbon-fiber tank up top, houses the fuel pump necessary for the KX450 motor to run like it should.

Hearing Wiseman describe the build in detail (and anguish) belies the simplicity of the finished product. Sitting on a slab of Arizona asphalt, it’s a deceptively basic machine. It weighs just 267 pounds—and holds a paltry 1.7 gallons of fuel. It’ll only take one person at a time, and it won’t take them very far. What’s far less apparent are the hours, weeks, and years of frustration that have been baked into every component—a familiar feeling for anyone who has built their own bike, as is that euphoric moment when your idea shakes the handlebars for the first time. Despite every detour and misstep, something abstract has finally been turned into something tangible.

Alongside the praise Robert has for the completed motorcycle, there’s a careful caveat: “It has a very raw feeling to it, from the vibration of the engine to feeling the pavement through the hardtail. I wouldn’t recommend it on the freeway or on a road with potholes.”

2012 Kawasaki KX450F
Back in its native habitat, Robert’s hardtail motocross bobber is the result of the effort of six years and countless setbacks.Spenser Robert

We find just the right place an hour north of Phoenix: a strip of black ribbon that wraps around Bartlett Lake, cutting through the very desert where Robert learned how to race. “Oh yeah,” he adds, “she does wheelies.”

True to his word, the bike lurches and rumbles, then wheelies away from a stop. It’s as electrifying as you’d expect a machine that entertains a professional racer to be. Words like “pleasant” or “refined” stay in their holster, but there’s no ignoring the allure of gliding the minimal bike through a set of corners. Less than half the weight of a Sportster, with similar power, stronger brakes, and a center of gravity hanging just barely off the ground, there seems to be genuine value in the concept of a dirt bike bobber. Throw some rear suspension into the chassis and swap out the power plant for a wide-ratio KTM 500 EXC-F with an electric start, and suddenly the concept makes even more sense. But then again, building something like this with the conceit that it makes sense might be missing the point altogether.

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When I asked how Robert thinks the thing would handle in the dirt, a mischievous smile mostly answers for him.

“Let’s find out,” he says, taking off down a nearby dirt road and sliding the bike sideways before the first corner. Even from a distance I could see the thing rattling his spine and threatening to shake apart the six years of progress it had taken to get to this point. It was a beautiful thing. While the “real” racebike may have been sitting on a kitchen shelf, proudly on display, its body double was finally back where it belonged: throwing roost and putting a smile on Robert’s face as if another championship was on the line.