Dual-Turbo BMW R100S Custom Hits the Auction Block — Seven Weeks, Two Turbos

A 1980 BMW R100S that was rebuilt in barely seven weeks — with a separate turbocharger for each cylinder — has surfaced for sale out of Miami, Florida, listed through Bring a Trailer on a bill of sale.

The machine came from Chris and Rebecca Canterbury, the pair behind Boxer Metal in Chico, California. They had originally planned to show a different bike at the 2016 One Motorcycle Show in Portland, Oregon, until that project shipped off to a customer in Guatemala. Seven weeks out from the event, they started over.

What’s Actually Under the Gold Paint

Beneath the metal-flake finish sits a 980cc air-cooled boxer twin that keeps its factory crankcase, cylinders and heads. Nearly everything bolted to it changed.

• Forced induction: Two T3/T4-style turbochargers, each with its own wastegate and blow-off valve
• Fueling: Electronic fuel injection run by a MegaSquirt MicroSquirt system, replacing the original carburetors
• Ignition and monitoring: Dyna electronic ignition, twin oxygen sensors, adjustable fuel-pressure regulator, oil cooler and boost gauges sunk into the tank
• Drivetrain: The stock five-speed gearbox and shaft drive stay, though the shaft now runs exposed and the final-drive housing has been reworked

With the turbos and their plumbing crowding the frame, Canterbury shifted the engine rearward and upward. The chassis itself was stretched six inches, dropped four inches, reinforced and locked into a hard tail. A 21-inch wire-spoke front wheel pairs with an 18-inch Lester alloy at the back, wrapped in a drag slick.

Suspension amounts to the BMW fork with heavier springs — plus whatever the tire sidewalls can absorb. Brembo discs feed through a Magura master cylinder, and there’s a front line lock fitted for burnouts. The bodywork includes a modified Dnepr fuel tank with black pinstriping hand-laid by Dennis Price, a Boxer Metal rear fender with an integrated solo seat, clip-ons, rear-set controls, an Acewell display and a 3D-printed headlight. The “Mom’s Rocket” lettering on the tank is a tribute to Rebecca.

A Show Bike That Never Quite Ran

Judges liked it. The bike took the Motorrad Award at The One Motorcycle Show and finished second in the Custom Motorcycle class at The Quail in 2016.

Getting it to run was another matter. The Boxer Metal team later confirmed the build was never fully sorted, which leaves the next owner with a project as much as a trophy. Whether that front line lock ever gets used in anger is anyone’s guess.

The Original R100S, Briefly

BMW revealed the R100S at the IFMA show in Cologne in 1976 as the follow-up to the R90S, slotting it beside the fully faired R100RS. The air-cooled flat twin was bored from 90 mm to 94 mm to reach 980cc, breathing through 40 mm Bing constant-velocity carburetors instead of the Dell’Orto units used before, mostly for emissions reasons.

Output started at 64 bhp at 6,600 rpm and rose to 69 bhp at 7,250 rpm from 1978. The frame kept its Norton Featherbed-inspired layout with thicker tubing, and stopping came from twin drilled discs with ATE calipers. Cast “snowflake” alloy wheels and a Brembo rear disc arrived for the 1978 model year.

In the United States the R100S carried a $4,195 price in 1977. It ran the standing quarter-mile in 12.97 seconds at over 103 mph. Production wrapped in 1980 after 11,762 units — shy of the R90S’s 17,465 — and the R100CS took over for 1981.