Knockout Krauser: A four-valve 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. 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...