The ADVXL: Biltwell’s Harley Sportster adventure bike

Harley Sportster adventure bike by Biltwell Inc.
Five years ago, the maniacs at Biltwell Inc. did something completely unhinged, by racing a Harley-Davidson Sportster 883 in the NORRA 1000 desert race across Baja California. And why not? The Californian parts and gear company knows their way around a Sportster—and they’re usually up for just about anything.

They’re also not stupid, which is why they took a second Sportster 883 along for the ride. Stripped down to its parts, the second Sporty rode in Biltwell’s chase van just in case something broke. But as it turns out, most of those parts were still sitting in the van by the end of the race.

Harley Sportster adventure bike by Biltwell Inc.
In true Biltwell fashion, the entire smorgasbord of spare and ex-race parts was then gathered into a pile and massaged into another fully functioning dirt bike, courtesy of regular Biltwell collaborator, Rob ‘Rouser’ Galan. Dubbed the ‘Spare Parts Sportster,’ that bike was enthusiastically thrashed all through the Mint 400, and the first two Biltwell 100 desert races.

The Sportster eventually started showing signs of the continual abuse it had suffered. So when Biltwell head honcho Bill Bryant started jonesing for an adventure bike to call his own, he figured it was time to give the unkillable 883 yet another makeover.

Harley Sportster adventure bike by Biltwell Inc.
“In the spring of this year, Rouser traveled from his surf lair in remote Panama to come up for his annual work trip in Temecula, California,” says Bill. “We brainstormed about what it would take to convert this semi-retired race-slash-thrash bike to become a more universal all-rounder.”

“First, we defined the mission; a street-legal bike that is capable of 300-500 mile days while having some modern features, extra fuel capacity, and the ability to haul plenty of gear. Of course, it had to be off-road capable and not lose any of the race-proven provenance inherited from the original Frijole, and also be comfy and competent on the highway.”

Harley Sportster adventure bike by Biltwell Inc.
Rouser tore into the 2003-model Harley-Davidson Sportster 883’s engine, rebuilding it with a 1,200 cc S&S Cycle kit. It breathes in via a CV carb with Rouser’s regular spread of go-to mods and exhales via a custom exhaust with a modified Cone Engineering muffler. The exhaust wears a Jet-Hot ceramic coating and has a kink in the end that points hot gasses away from the rider’s luggage.

The 883 also benefits from Buell XB valve covers and breathers, a Dyna 2000i ignition, and a Cycle Electrics charging system. It sports a Rekluse clutch, a Honda XR400 oil cooler, and a lightweight Antigravity battery.

Harley Sportster adventure bike by Biltwell Inc.
It stands way taller now, thanks to a set of 2005-spec Honda CRF250F forks and a pair of Elka rear shocks. Giga Cycle hooked Biltwell up with a set of custom triple trees with a slightly more relaxed head angle, and Biltwell moved the steering stops to improve the bike’s turning radius.

The laced rims use 21F/18R Excel rims, wrapped in Metzler MC360 tires. Biltwell also installed a Giga Cycle rear brake carrier, Galfer discs, and a GPR steering stabilizer.

Harley Sportster adventure bike by Biltwell Inc.
With extra power and suspension travel on hand, Bill wasn’t about to neglect the chassis. The frame and swingarm were beefed up in key places, and the oil tank was attached directly to the frame rather than via the OEM rubber mounts. It’s a proven mod that Biltwell used on their NORRA 1000 bike—as is the practice of swapping the push-in oil tank cap for an aluminum one with a threaded bung.

“These oil tank mods are often overlooked by novice desert racers hopping up a Sporty,” Bill explains. “All it takes is one tip-over for the stock oil cap to pop off and all is lost in the middle of nowhere.”

Harley Sportster adventure bike by Biltwell Inc.
Burly crash bars sit up front, with a modified skid plate from the now-defunct Hugo Moto mounted lower down. Biltwell turned the gear-shifter around, GP-style, to tuck it in tight, and added a pair of wide and grippy Hugo Moto foot pegs.

The Sportster’s radically redesigned cockpit reads like an adventure rider’s Christmas list. The mods include a Manic! Rally navigation tower, with two Baja Designs Squadron Pro lights poking out the front, and two more mounted on the crash bars as fog lights.

Harley Sportster adventure bike by Biltwell Inc.
Tucked behind the fairing is a Garmin Zumo XT2 GPS unit that doubles up as a speedo, with a bespoke switch panel that uses aircraft-style circuit breakers. The crew also added oversized bars, hand guards, and Biltwell grips with heated grip liners. “It sounds pretty bougie for chopper types, but they sure are nice when it’s chilly,” says Bill.

All that was left was to prime the Sportster for long days in the saddle. “We went round and round about how to solve the extra fuel capacity issue,” says Bill. “We didn’t want a strangely huge plastic tank—it just wouldn’t look or feel like a Harley.”

Harley Sportster adventure bike by Biltwell Inc.
The simplest solution was to attach two one-gallon Rotopax fuel cells to an SW-Motech top box. The top box was then mounted to a custom-made rack, which extends downwards to accommodate a pair of Biltwell EXFIL-18 saddlebags .“This lends itself to roughly 200 miles without an external gas stop,” Bill adds. “I need a snack about every 100 miles or so anyway.”

Resplendent in Subaru ‘Adventure Green’ and flat black, courtesy of Pete Finlan, Biltwell’s ‘ADVXL’ is as purpose-built as they come. But how does it ride?

Harley Sportster adventure bike by Biltwell Inc.
“Rob’s rebuild with the S&S 1,200 cc Hooligan kit makes this bike way more peppy than the original Frijole,” Bill confirms. “The gearing is perfect for mixed-use. It’ll run 70 mph all day on the highway without feeling taxed, but still has plenty of grunt down low to get this 500-pound wannabe dirt bike out of tricky situations off-road.”

“Rob’s attention to detail on the build confused fellow riders on a recent ferry ride in the Pacific Northwest. Most of them insisted that it must be a new motorcycle and had a hard time believing it was a 20-year-old Sporty.”

Harley Sportster adventure bike by Biltwell Inc.
“This motorcycle may have been born and raised in the deserts of So Cal and Baja, but it’s getting a new lease on life up on the Olympic Peninsula of Washington State. I moved up here to the upper left in Port Angeles this summer and the ADVXL is the bike that gets the most use so far since it behaves so well in all environments.”

“I’ve yet to take it on any multi-day epic adventures but that is absolutely the plan!”

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Harley Sportster adventure bike by Biltwell Inc.

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