The BMW R1100S

The BMW R1100S was released in 1999 as an indication of the direction the German marque would take into the 21st century. It was fitted with the most powerful boxer twin BMW had made up until that point, producing 98 hp and 72 lbf.ft from its 1085cc capacity, and it was mated to a 6 speed gearbox that sent power back to the rear wheel via a shaft drive.

Underneath its half fairing, the BMW R1100S is a slightly unusual motorcycle – certainly by 1990s standards. The engine is a stressed member with an aluminium subframe, Telelever front suspension, and a single sided swingarm with a subframe-mounted monoshock.

The exact niche BMW was targeting was “sports tourer”, however some called the R1100S a “sporty sports tourer” as it was quicker than almost anything else in the niche. With a dry weight of 208 kilograms (459 lbs) and a half fairing with decent wind protection, the R1100S is ideally suited longer distance riding, and can easily sit on 80 mph at 4000 RPM.

The Moto Adonis BMW R1100S

Due to the relatively complex nature of the model, few custom motorcycle garages have taken a swing at customising them. So when Marc walked into Moto Adonis and mentioned he wanted his R1100S turned into a more classically styled cafe racer, they jumped at the chance.

As with most builds, this one started with a teardown and an inspection of parts. They realised a new subframe would need to be fabricated to accommodate a new seat and rear cowl. The stock fuel tank was removed and placed on the pile with the fairing, windshield, seat, exhaust, and handlebars.

The fuel tank from a BMW R100S police bike was sourced and fitted, keeping the DNA intact and giving the bike an unmistakably BMW look. This new tank needed an entirely new bottom end to fit the original fuel pump, whilst still leaving room for the engine and ancillaries beneath.

The new seat and rear cowl was made in-house, the latter incorporating an LED strip along the rear to take care of brake and indicator lighting. The cowl also holds the new lithium-ion battery and some of the electrics, and a new 2-into-1 exhaust was welded up, designed to stick closely to the side of the engine and exiting out the left side through a Shark muffler.

The stock airbox made way for a new electrics box, and the twin carburettors now breathe through pod filters to increase air flow. When combined with the exhaust and Power Commander V, the engine now produces appreciably more than it did in stock trim.

A matching pair of Hagon shocks replaced the factory units front and back, and a new set of clip-ons was added with discrete m.switch controls provided by motogadget. The original instrument cluster was replaced with a single Acewell unit mounted to the lower right side, and a grill-covered headlight replaced the stock unit.

The completed bike is now back in Marc’s hands, and his girlfriend is now planning on getting her Yamaha TR1 reworked by Moto Adonis in a similar fashion. If you’d like to see more from the team or commission your own build, you can click here to visit their website.