Airhead Reborn: BMW R80RT by MotoBrix

MotoBrix rebuilds a botched BMW custom…

Though the BMW airheads were considered modern classics even before their production ended in the late 1990s, engineers and enthusiasts probably never considered that the air-cooled boxers would have such a renaissance in the customs world of the 21st century. Two decades into the 2000s, we’ve seen more cafe racers, scramblers, and street trackers built from airheads than any other platform.

Of course, popularity can lead to over-saturation, and we’ve admitted that it’s harder for us to get excited about airheads than other builds — we’ve just seen so many of them. On the other hand, when an airhead does strike us, we know it’s managed to stand out from the pack — a true special, like this R80RT from Toronto-based workshop MotoBrix.

Funny enough, headman Brian Kates of MotoBrix admits that he fell unintentionally into customizing airheads:

“I like to joke about it, but I never sought out to build custom bikes based on BMW airheads. I was always more interested in modern Japanese sport bikes and later developed a preference for vintage Yamaha and Kawasaki-based custom projects.”

However, after building an R75/5 we featured on BikeBound and buying himself an R80ST daily rider, Brian says his commissions for the past two years have been almost entirely airheads. This ’86 R80RT was built for Mischa Couvrette, a furniture designer, entrepreneur, and the creative director of Hollis+Morris, whose designs have been featured in Dwell, Architectural Digest, Azure, and more. As befits a professional designer, Mischa not only commissioned the build, but Brian cites him as a co-designer who brought his own vision to the build:

“Mischa wanted to mix the complexity and chaos of a full custom pie-cut exhaust with simplicity and elegance for the rest of the bike. A less is more approach, similar to his design philosophy at his own company…”

The unique exhaust certainly drew us to this build, as did the compact, muscular lines of the overall silhouette. Below, Brian gives us the full story on the build, along with photos from Gary Davidson (alley shots) and Naomi Finlay (warehouse shots).

BMW R80 Custom: In the Builder’s Words…

I like to joke about it, but I never sought out to build custom bikes based on BMW airheads. I was always more interested in modern Japanese sport bikes and later developed a preference for vintage Yamaha and Kawasaki-based custom projects. As time went on, I found myself surrounded by more and more vintage BMW owners and enthusiasts in Toronto, and eventually was commissioned to build an R75/5 featured on BikeBound. I myself bought an R80ST as a daily rider, and for the past two years have almost entirely attracted clients wanting customs based on airheads.

Which is why when Mischa Couvrette, a furniture designer and entrepreneur also from Toronto, saw my work, he was interested in having me build him a custom BMW. Mischa had already tried to build a custom bike himself years prior, first attempting modifications on a 1979 Yamaha SR500. He did what he could but wasn’t totally satisfied with the outcome. He knew that this time he wanted to enlist the help of a professional builder.

With a reasonable but not unlimited budget, we wanted to focus on pushing the boundaries in a few key areas, while keeping the rest of the design as simple and clean as possible. Inspired by the wild exhaust work from some other notable custom shops, the idea unfolded organically. Mischa wanted to mix the complexity and chaos of a full custom pie-cut exhaust with simplicity and elegance for the rest of the bike. A less is more approach, similar to his design philosophy at his own company, as creative director of Hollis+Morris. Mischa created a concept image from a collage of his favourite components from other bikes using Photoshop, and handed it to me to use as a basis for the design.

First, we picked a donor bike, a 1986 R80RT monoshock. The engine was in good condition, but the front end was a bit of a hack job. The previous owner had installed a cobbled-together vintage Kawasaki KZ1000 front end. Besides the problem of mismatched wheels, the PO had stuffed hose clamps to fill the space between the bearing races and the steering stem.

To get the look back to stock, and restore safety, I found a K100 front end, which has the same front wheel as the original R80RT. The forks were then shortened internally 3” to get the stance just right. The rear of the tank was also lifted with a modified bracket, to give a continuous line from front to rear angled slightly up.

The frame was cleaned up, and a custom subframe welded on. The PO in true form had also hacked off the kickstand along with the pivot pin, and so a new custom stand was made. The centre stand was removed, and a battery box was made for the Shorai Lithium battery, under the transmission.

The engine was taken apart, down to everything except for the crankcase and crankshaft, vapour blasted, painted, and put back together with all new seals, and components. Luckily the engine was in good shape; most likely untouched from previous owners.

I spent a few weeks building a full custom stainless steel pie-cut exhaust. After about three attempts to build equal length headers, and coming up with shapes that looked more like deformed ram horns, I finally settled on a design with unequal length headers.

I get a lot of questions about whether it performs alright, and if anything, it might have even improved low end performance. Our original plan was to build an undertail muffler, but it made much more sense with this design to place a shorty muffler on one side of the seat.

For this build I decided to try a new electrical unit from Nuut in Canada (Now called NWT Cycletronic) instead of the usual Motogadget M-unit. I installed their Tricky system, which allows for a simple two-button setup, which cleans the handlebars up considerably. The ignition is controlled by a Motogadget M-lock key fob. I scrapped the original throttle and master cylinder and replaced them with a dual-pull throttle from Messner Moto, as well as a sleek Grimeca front master cylinder.

The engine was cleaned up with an airbox cover from Better Boxer, and Uni foam filters. With the handlebar setup made as clean as possible, we had to locate the choke lever somewhere else. We ended up retrofitting an earlier /5 choke lever bolted to a custom-welded plate on the side of the airbox cover. It looks similar to the /5 setup, and for the most part you wouldn’t know it was custom. Additionally, all the control cables were made from scratch to fit the fully customised setup.

The seat was made from a stainless steel pan, with a separate steel under pan to hold the electrical components, and upholstered in leather by Devin at Uneek Upholstery. I was very deliberate with this build to make the wiring as neat as possible, and used heat shrink and wiring loom to cover organised groups of wire. I’ve learned from past builds that keeping wiring neat and clean can make all the difference. It also helps when trying to diagnose problems if they ever do come up.

It took Mischa about 20 hours of riding before he truly understood what the bike had become. We had to adjust the settings a bit on the YSS rear shock to soften the ride, and still will probably have to swap in softer fork springs to truly dial in the suspension properly. Although these bikes aren’t known for being all that powerful, the exhaust has brought out a bit more grunt on an already torquey engine. This particular engine also happens to run quite smoothly, even as airheads go. The bike is loud, but not overly obnoxious, with more of a pleasant growl.

We’re both extremely proud of how the bike turned out, and in the end Mischa has a bike that not only looks great, but that he’s able to ride regularly as a commuter to and from work.