Flying Brick to Top Gun: Jet-inspired K100 from Jerem Motorcycles…
Introduced in 1987, the BMW K100 was quite unlike any motorcycle BMW Motorrad had ever produced — or any other company, for that matter. At the time, BMW’s bread-and-butter boxer twins were outdated, and the company’s reputation for producing superior, premium-priced motorcycles was wearing thin. They were losing market share and sales at an alarming rate.
BMW needed a modern, liquid-cooled, clean-burning four-cylinder motorcycle to compete with the Japanese manufacturers, and they leaned hard on their automotive expertise to help produce it. In fact, the first prototype utilized a Renault X-Type engine from a Peugeot 104! That gave them a successful proof of concept for the layout: an inline four-cylinder engine laid on its side in the frame, with the valve covers on one side and the crankcase on the other — a unique visual that led to the K bike’s well-known nickname, the “Flying Brick.”
Some of the same engineers who’d worked on BMW’s Formula Two race engine were enlisted to design, develop, and test the 987cc, 90-hp engine for the K100. It used Bosch Jetronic fuel injection like the BMW 3-series cars of the era, and featured a breaker-less electronic ignition system.
It’s a testament to the K100’s engineering that many of these bikes are still in service 35 years after their introduction:
“They were very well made and the second hand values are still relatively low. It’s a bike that’s built to last and is arguably more reliable than the Japanese bikes of a similar age.” —BSK SpeedWorks via MCN
While the original machines were autobahn cruise missiles with full fairings, modern K100 customizers have been stripping them down and turning them into Bavarian hot rods. This one comes to us from our friend Jérémie Duchampt of France’s Jerem Motorcycles, and it’s loaded with details.
One of the signature aspects of the build is the air intake, which has been relocated to the tail! A custom stainless steel intake pipe runs under the seat to the air flow meter, while an LED taillight has been integrated into the air filter itself! The result looks something like a jet afterburner, complete with air intake scoops, so it’s no surprise that Jérémie nicknamed the bike “Top Gun.”
The suspension and brakes have also been updated. The bike is now running inverted forks and brakes from a Suzuki TL1000S, with a Yamaha R1 rear shock mounted horizontally via a custom-made mounting system — a modification we’ve seen on several of these bikes lately. The front wheel is from a GSX-R, while the rear comes from a BMW K1200GT.
Jérémie also relocated the side stand to the right side of the bike, as the original location let oil seep past the rings, causing the bikes to smoke at startup.
All of the lighting has been updated to LED, a custom fiberglass undertank box holds the electronics, and the bike now boasts a TENET management box and keyless start system with remote control. It even has a nifty illuminated BMW lower engine logo.
The engine, frame, wheels, and swingarm were all painted in a satin black epoxy, while the bodywork is finished in Renault’s iconic Alpine blue — a hue with quite the history. All in all, this one stunning ‘Brick, well deserving of the name “Top Gun.”
BMW K100 Cafe Racer: Build Sheet
Suzuki 1000 TLS inverted fork
Front rim: Suzuki GSXR with Suzuki 1000 TLS brake system
Modified Triumph front fender
BMW 1200 GT rear wheel
Yamaha R1 shock absorber with custom-made steel mounting system
Tailor-made rear plate support + mudguard
Modification of the frame for the AR shock absorber and the custom rear shell
Modified side stand — change of side due to the original problem (oil in the pistons)
Change of right and left stalks
LED headlight + Custom CNC aluminum supports
LED rear light/stop integrated in the air filter
Front LED turn signals + central flashing modification
Rear LED turn signal integrated in the AR loop
LED license plate lighting
New TENET counter beam management box
Keyless start system (with remote control)
Custom-made fiberglass undertank box for the various electronic boxes.
Removal of the ABS system with modification of the wiring harness
Removal of the air box
Air filter integrated into the rear hull
Custom-made stainless steel air intake pipe, and under-seat pipe with air flow meter.
Custom stainless steel 4-in-1 exhaust modification with vintage silencer
Machining of parts for adaptation of the fork
Tailor-made rear shell with small side air scoops
Tank moved back and raised on the front part by 2 cm
Carbon black BMW logo on tank
Illuminated BMW lower engine logo
Vintage CNC mirrors
Blue Renault Alpine fuel tank and rear cover
Carbon sticker decoration
Rims painted in black epoxy oven
High temperature yellow brake calipers
Satin black epoxy frame
Engine, Swingarm, etc.: Satin epoxy black