The R100X: A BMW boxer enduro bike from an F1 engineer

Custom BMW R100 enduro bike by Ben Norton
There’s something special about taking a classic motorcycle, and transforming it to the point that it’s fit for an entirely different purpose than it what was originally created for. It’s the difference between customization and re-engineering; modern materials and processes augment vintage style, and every last nut and bolt is carefully considered. And that’s exactly the way that Ben Norton likes to do it.

His latest project started out as a 1995 BMW R80R, but ended up a very different animal. It’s the same radical approach to custom bike building that we saw with his last build—a jaw-dropping supercharged BMW R100.

Custom BMW R100 enduro bike by Ben Norton
The secret to Ben’s approach lies in his vocation. By day, he’s the chief engineer at a works Formula One team, where the pressure to make things perform better is immense. After hours, he unwinds by tinkering in his home garage, under the workshop name 10 ’til 12.

So while the rest of us are sleeping or binge-watching Netflix, Ben’s figuring out how to build insane machines like this. He calls it the ‘BMW R100X,’ and its off-road inspired vibe is not just for show.

Custom BMW R100 enduro bike by Ben Norton
Ben lives in the UK now, but he was born in Zimbabwe, in the south of Africa where dirt roads abound and off-roading is a big deal. His goal on this project was to build a lightweight desert racer, with an emphasis on practicality and fun. “And to go back to my African off-road heritage,” he adds.

“It’s a hybrid of old and new technology, while trying to retain the airhead character and BMW’s off-road legacy. The ‘X’ is a nod to the BMW G450X enduro bike, which was stuffed full of innovative engineering—much like I feel the R100X is.”

Custom BMW R100 enduro bike by Ben Norton
There’s very little left of the original BMW R80R donor bike. Ben kept the engine block, transmission casing and some of the frame—but the rest is a mix of transplanted, upgraded or bolt-on parts.

The work done to the engine alone could fill volumes. It started out simple enough, with a 1,000 cc kit from Siebenrock, running a 9.5:1 compression ratio. Ben also added a Silent Hektik programmable ignition and alternator system, and the starter motor from a Toyota Denso… and then things escalated.

Custom BMW R100 enduro bike by Ben Norton
Ben designed his own billet aluminum timing and front covers for the boxer motor, which were CNC-machined by a good friend, Fredrik Larsson at Aximech in Sweden (it helps to have good contacts). That shaved 3.5 kilos [7.7 lbs] off the engine’s weight, and added extra clearance for the front wheel. The engine block was cut down too, to save even more weight.

Vintage BMW fans will notice that the engine’s been pitched nose-up, in a bid to improve ground clearance and front wheel travel. The oil sump and bash plate are also one-off parts, again designed to offer more ground clearance, but also to sit perfectly in line with the frame and exhaust. The transmission is all-new inside too, with revised gear ratios.

Custom BMW R100 enduro bike by Ben Norton
Higher up, an oversized K&N filter sits on a custom mounting plate, with quick-change tie down straps for breezy services. Hanging off the left side of the bike is a beefy titanium muffler from SC-Project, hooked up to mandrel-bent stainless steel headers.

To say that the drivetrain looks factory fresh would be an understatement. It has a purpose-built look to it, helped along by a generous helping of Cerakote finishes.

Custom BMW R100 enduro bike by Ben Norton
Moving to the frame, Ben set about removing anything that wasn’t fit for purpose. On went a new subframe, built around laser-cut braces to increase stiffness and save weight. What isn’t as obvious, are the other places where the frame has been reinforced, and where extra brackets have been welded on to hold the myriad add-ons this bike sports.

Out back sits the single-sided swingarm and final drive from a BMW R100RT. It’s been extended by 100 mm and linked to a custom-made Penske shock, for a whopping 225 mm of rear wheel travel. A set of WP Suspension forks, taken from a KTM 690 Enduro R and Cerakoted to match the build, offer 250 mm of travel up front.

Custom BMW R100 enduro bike by Ben Norton
The R100X rolls on a 21F/18R wheel set, perfect for off-road shenanigans. They use Excel hubs, with a custom-made hub (designed by Ben and machined by Aximech) at the rear, that allows Ben to run fewer and larger spokes than stock.

The front brake uses a Brembo caliper and a 320 mm disc. The rear still uses a drum brake, but it’s been converted to hydraulic by way of an AP Racing master cylinder and a Willwood slave, and setup so that there’s no change in brake actuation with the increased suspension travel. All of the brake lines are custom, using Atec motorsport fittings.

Custom BMW R100 enduro bike by Ben Norton
The bodywork is remarkably run-of-the-mill by comparison—but it works beautifully. Plastic fenders from Acerbis do duty front and rear, while a BMW R65 fuel tank, chosen for its smaller capacity and slim, angular lines, sits center stage. Pro-Kustom shot the minimalist paint job, offset against satin black powder-coating on the frame.

To get the seat inch-perfect, Ben first designed it using CAD software, then had a laser-profiled mold made. Tom Hurley Custom Seats was responsible for the final product. It uses an alloy seat base, with a synthetic material on top to give it a modern dirt bike look and feel.

Custom BMW R100 enduro bike by Ben Norton
The cockpit features a burly set of Renthal handlebars, fitted with Acerbis hand guards, a Domino racing throttle, and Rebelmoto switches. The switches are particularly clever—they include color-coded LED backlights that act as the bike’s warning lights, so there’s no need to have separate warning lights wired in.

A pair of Baja Designs headlights sit up front. There’s a full complement of Motogadget goodies too—from the control unit that runs the motorsport-spec wiring loom, to the dash, keyless ignition and turn signals.

Custom BMW R100 enduro bike by Ben Norton
And then there are all the ‘small’ things—like the main electronic module’s custom-made aluminum carrier, the billet aluminum and fully-adjustable gear lever, and the ‘cookie cutter’ style fuel cap. An Antigravity battery hides under the seat, all the bike’s breather lines are plumbed into the central air filter for maximum protection… the list goes on.

And if you’re wondering if all that weight saving worked, it did. Ben’s BMW R100X clocks in at 160 kilos [353 lbs]—a whopping 40 g [88 lbs] saving over the stock bike.

Custom BMW R100 enduro bike by Ben Norton
It’s rare to see a custom bike where the engineering is allowed to shine at this level, and where the bike’s performance is sure to match how wild it looks. But it’s what we’ve learned to expect from Ben—and it’s what he expects from himself, too.

Ben Norton Instagram | Images by Christopher Bailey

Custom BMW R100 enduro bike by Ben Norton

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