/Knockout Krauser: A four-valve R100 from Ironwood

Knockout Krauser: A four-valve R100 from Ironwood

A four-valve Krauser-powered custom BMW R100 from Ironwood
Ironwood Custom Motorcycles get frequent requests for their signature R-Series BMW bobbers. But when a regular client rolled in with a unique donor, shop boss Arjan van den Boom knew he had to up the ante.

The bike in question was a 1982 BMW R100—but with a very special motor. It was packing a full Krauser upgrade, complete with four-valve heads, Nikasil barrels and an electronic ignition.

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
The
client was a BMW and Porsche fanatic with very discerning taste. So whatever the Dutch shop built would need to be special.

Arjan and co. answered with a sharp, low-slung bobber that follows the typical Ironwood aesthetic, but with a slew of trick upgrades.

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
First, the boxer shed all of its 80s bodywork in favor of a more minimalist setup. Ironwood swapped the /7 fuel tank for a /5 unit, and added a solo seat with upholstery by Marcel from
Miller Kustom Upholstery. They built a new pair of fenders too, with hand-made struts supporting them.

Out back, the crew ditched the subframe and fabricated a new seat support and shock mounts. The BMW now sits on a pair of new rear shocks from TFX.

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
The front forks are Öhlins, lifted from an Aprilia Tuono. Ironwood kept the stock wheels, but wrapped them in modern, street-biased Continental Classic Attack tires. The front brakes were upgraded to Brembo units, with 320 mm discs for extra bite.

The highly tuned motor didn’t need any internal work, but on the outside it was cleaned up and re-done in black, with gold for the valve covers.

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
Ironwood installed a pair of Mikuni TM40 flat side carbs, and DNA Filters supplied a set of pod filters with gold tops that feature Ironwood’s logo. There’s an extra hit of gold in the form of a custom crankcase breather tube.

The exhaust system’s a pretty special touch too. Marcel van der Stelt from The Custom Factory was pulled in to build a stainless steel two-into-one system, which terminates in an aggressive-looking Ixil muffler (originally designed for the Yamaha XSR700).

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
Ironwood also rewired the bike from top to bottom, with a
Motogadget m.unit control box at the heart of the system. All the lights are LED, with a Koso ‘Thunderbolt’ headlight, Kellermann taillight/turn signal combos out back, and extra running lights on the frame.

There’s a whole lot of Motogadget stuff in the cockpit too—including the speedo, switches, grips, bar-end turn signals and mirrors. The grips have been wrapped in the same leather as the seat, and sit on a set of CNC-machined clip-ons. And the speedo’s integrated into a custom-machined top yoke.

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
We were lucky enough to see this bobber in the metal at BMW’s
Pure&Crafted event in Amsterdam, and spotted a lot of details that you’d only notice if you were close. The leather battery box is one nice touch, but the small leather cable holders are even more thoughtful.

Ironwood opted for a simple an elegant paint job: a coat of Porsche Pasha Red, laid down by Jacco from Royal Kustom Works. If you’re a Porsche enthusiast, you’ll know that this particular hue was introduced in the 1950s and often paired with tan leather back in the day.

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood
It’s not every day that you see a pair of Krauser’s peculiar four-valve heads roaming the streets. And seeing them in such a suave modern build is an even more rare treat.

Equal parts aggressive and elegant, this Beemer is a solid entry into Ironwood’s ever-growing portfolio.

Ironwood Custom Motorcycles | Facebook | Arjan van den Boom Instagram | Images by Paul van Mondfrans Lindén

A four-valve Krauser-powered custom BMW R100 from Ironwood
A four-valve Krauser-powered custom BMW R100 from Ironwood

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