Mad Science: A Harley Sportster Grand Prix racer by a nuclear chemist

Harley Sportster Grand Prix racer by Corban Gallagher
As a nuclear chemist with clients spanning multiple industries, Corban Gallagher’s day job calls for ingenuity and precision in equal measure. So when he occasionally takes a break from work to build custom motorcycles, he typically ends up creating machines that are both outlandish and well-engineered—just like this totally bonkers Harley Sportster ‘Grand Prix’ racer.

Just like his debut custom build, Corban built the Sportster specifically for the annual Handbuilt Show. “Because it’s held in Austin on the same weekend as the American MotoGP, I wanted to do something that was in the spirit of both events,” he tells us. “I thought it would be fun to build the most low-budget ‘GP’ bike ever, by using almost exclusively salvaged parts.”

Harley Sportster Grand Prix racer by Corban Gallagher
The starting point of the project was a wrecked 1996 Sportster frame and the rear shock from a 1998 Ducati 900SS. With a 1997 Sportster XL1200 engine sourced from a junkyard, the project was more or less underway. But first, Corban had to bring the 27-year-old V-twin up to spec…

“Once I had the crusty motor torn apart, I asked Hammer Performance to put a package together for me based on a set of Buell Thunderstorm heads I had on the shelf,” he tells us. “It now has 1,275 cc barrels with domed pistons, a racing clutch, Andrews cams, a 42 mm Mikuni carb, and a few other bits and pieces.”

Harley Sportster Grand Prix racer by Corban Gallagher
Adamant about using the Ducati shock, Corban’s next big task was to build a new mono-shock rear end to put it to use. Cannibalizing the lower shock mount and brace from the Ducati 900SS, he built a new swingarm that could accommodate not only the shock but also a 200 mm-wide rear tire. The new swingarm ended up being about 3” longer than the OEM Harley unit.

Although it’s a small piece, a lot of thought went into the upper shock mount. It wraps around the frame’s backbone for extra strength, and serves as a mounting point for the front section of the all-new subframe. Aside from having to straighten out one of the down tubes at the front, Corban left the rest of the frame stock.

Harley Sportster Grand Prix racer by Corban Gallagher
The rest of the rolling chassis parts come from a 2003-model Buell XB9R. “I chose these wheels mainly because of that insanely cool front brake rotor,” Corban tells us. “I used the lower triple tree from the Buell, but a custom steering stem and flat top upper triple tree from Bare Knuckle Performance was needed to mate everything up properly with the Harley’s neck.”

With everything now in place, Corban turned his attention to the bodywork, putting the bike together with a delightful mix of styles spanning multiple decades of racing.

Harley Sportster Grand Prix racer by Corban Gallagher
The front fairing comes from Airtech Streamlining and is designed for 1970s Triumph and BSA race bikes. Those motorcycles aren’t quite the same shape as a 1990s Sporty, so Corban had to do a considerable amount of massaging to get the fairing to fit. He eventually managed to position it so that the windshield would sit impossibly low, the top edge of the side section would run parallel to the seat, and the belly pan would fit perfectly under the engine.

“The fairing also had a really slick cutout in the front, originally for the Triumph’s oil cooler,” says Corban. “Instead, I was able to find an off-road LED light bar that fit perfectly inside it, and cut the lens out of smoked polycarbonate. It made it look kind of like Robocop—which is never a bad thing.”

Harley Sportster Grand Prix racer by Corban Gallagher
Plan A was to use an old Norton Commando fuel tank, but the positioning of the rear shock laid waste to that idea, because it didn’t leave any room for a separate oil tank. So Corban pivoted, installing a 1950s Norton Manx split tank that could carry both the fuel and oil. The tail section is an off-the-shelf part and houses the battery tray.

The rest of the parts list includes Woodcraft clip-ons, Sato Racing rear-sets, and a chunky 5” Autometer tacho. The brutally short exhaust headers were made by Kinetic Motorcycles, and reportedly sound downright maniacal.

Harley Sportster Grand Prix racer by Corban Gallagher
Just like his last Handbuilt Show project, Corban opted to handle all the paintwork on the Sportster himself. “I painted my last bike in the middle of my machine shop at work, and wrestled with airborne dust and debris,” he says. “So for this one, I thought it would be better to spray it in my backyard—but I learned my lesson, and have since gone back to painting in my machine shop.”

“I felt that a bike as cartoonishly absurd as a Harley GP bike made from junk deserved a cartoonish paint job as well. I chose my color palette from a ‘Spy vs Spy’ comic I saw. The whole page of the comic was beautifully balanced with the flat gray tying the black and white together, so I approached the paint and graphics with the intention of creating the same level of balance.”

Harley Sportster Grand Prix racer by Corban Gallagher
Once again, Corban’s shown that he not only has a wild imagination and a sharp eye, but a deft hand too. This Harley Sportster race bike is completely off the wall, but somehow also impressively elegant. We’d love to see it go around a track at full tilt, but unfortunately, Corban’s not quite ready to ride it in anger yet.

“The bike still needs to go through all the break-in recommendations Hammer Performance prescribed before I take it to a track and run it hard,” he explains. In the meantime, he has a slew of other projects to keep his hands from being too idle.

Harley Sportster Grand Prix racer by Corban Gallagher
“I’m finishing up a ground-up restoration of a 1976 Harley Electra-Glide, and I have a donor Triumph Thruxton and a wicked cool custom frame from Bitter-End Choppers on deck. I’m also trying to work out an amphibious beach chopper idea that I have had knocking around upstairs; still trying to find the sweet spot of buoyancy and gnarly power.”

Corban Gallagher Instagram | Images by Myke Toman

Harley Sportster Grand Prix racer by Corban Gallagher

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