Transforming a Slash-5 from “tame touring bike into a bit of an animal.”
In 1970, BMW introduced the Slash-5 series, which included the R50/5 (500cc), R60/5 (600cc), and the R75/5 (750cc). The bikes were a revolution for BMW, and arguably the company’s first “modern” motorcycles. They had an all new flat-twin boxer engine with chain-driven cam and iron-lined alloy cylinder barrels, 4-speed transmission with shaft-drive, telescopic forks, and a 12-volt alternator with an electric starter.
“The overall effect was a machine that, at a little over 400 pounds dry, was much less bulky than the /2, had more power, handled extremely well and had better clearance thanks to the cylinders being farther away from the ground.” —Motorcycle Classics
Enter our new friend Brian Kates of Toronto’s Motobrix, who worked in mechanical/biomedical engineering until he discovered his passion for welding and fabrication:
“I took some welding courses to try to learn how to customize my 1st Gen SV650, and things kind of snowballed from there. I quit my job as a biomedical researcher and devoted all my time to metal fabrication, building custom motorcycles and furniture.”
While Brian does a lot of custom architectural work through Root 2 Engineering to keep the shop going, he really loves building bikes. The bike you see here is a ’71 R75/5 originally owned by his friend Emrah Gonulkirmaz (@windfaces), a creative director who was interested in building a vintage airhead with Brian. Then, while riding in Toronto, he ran into Sivonn Ra, who loved the bike:
“They got to talking and before long Sivonn had commissioned Emrah and me to build him a custom out of Emrah’s bike.”
While we see a ton of custom airhead builds, we see very few from the older Slash-5 series, which was only produced from 1970-73. What’s more, Brian and crew had only seen these types of builds on the web and ‘gram, and were excited to do one out of Canada.
“The idea was also to keep the design as simple as possible, with only the bare essentials; classic style with some subtle modern touches.”
The full build details are listed below, but highlights include a removed subframe with shock mounts and seat pan welded to the powder-coated main frame, Uneek Upholstery saddle with integrated LED, rebuilt gearbox, upgraded Enduralast charging system with Motogadget M-unit Blue, and custom top yoke with a bracket made of bent rod to hold the different components — a signature element:
“With the R75, I started creating every bracket in a sort of organic style out of round stock. I bend each piece on the go and shape things in a way that works. The custom LED headlight mount — something that’s become a bit of a signature piece — came about in the same way. I wanted to push the headlight in as far as possible, and came up with a way of holding the headlight without having a bucket.”
Nicknamed the “RA75” after the owner’s last name, this R75/5 is now a different beast altogether. Brian says the changes have really woken up the once-tame BMW touring machine:
“The free flowing pipes, combined with the tiny seat and somewhat clunky 4-speed gearbox, have somehow turned a tame touring bike into a bit of an animal.”
Below, we get the full story on the build from Brian himself, as well as more photos from Mark Luciani (@lightandgears).
BMW Slash 5 Custom: Builder Interview
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
I currently run a welding and fabrication shop in Toronto, but I wasn’t always a hands-on kind of guy. My background is actually in Mechanical Engineering and Biomedical Engineering.
I started riding motorcycles — mainly sportbikes — in my mid 20s. A few years later I took some welding courses to try to learn how to customize my 1st Gen SV650, and things kind of snowballed from there. I quit my job as a biomedical researcher and devoted all my time to metal fabrication, building custom motorcycles and furniture. It happened fast and kind of organically. I shared a shop with an experienced metal artist for a few years, and finally took the plunge in 2020 and opened up my own custom metal shop.
My business is called Motobrix; I started by building my own custom motorcycles, but these days I also focus on custom parts and welding and fabrication support for other people’s custom builds. I would love to build bikes full time, but to keep the shop running, I have to do a lot of custom architectural metal work; in other words I make a ton of coffee and dining table bases, and the occasional railing. The architectural projects are done under another company name: Root 2 Engineering.
• What’s the make, model, and year of the bike?
BMW R75/5, 1971.
• Why was this bike built?
The bike was originally owned by a friend of mine, Emrah Gonulkirmaz. He had fixed up the R75 in its mostly original form, and became interested in the custom work I was doing on other bikes. As a creative director in his daily life, he had expressed interest in doing a custom project with me on a vintage airhead. A few months later, while riding in Toronto one day he ran into Sivonn Ra, who was admiring the bike. They got to talking and before long Sivonn had commissioned Emrah and I to build him a custom out of Emrah’s bike.
• What was the design concept and what influenced the build?
The concept was heavily influenced by some of the BMW cafe racers being made in Europe. We’d seen lots of custom 1980s R80s and R100s being made, but not too many early airheads being customized at the time, like the /5. Sivonn really liked the style of these European customs, and wanted something similar; so we decided on building something in a typical cafe racer bobber style, but with some of the classic components kept from the early bikes, with drum brakes front and rear on spoked wheels.
We’d only seen these custom airheads on Instagram posts and in blog posts, so we were excited to make something of similarly high quality at home in Canada. The idea was also to keep the design as simple as possible, with only the bare essentials; classic style with some subtle modern touches.
• What custom work was done to the bike?
- The subframe was removed, and custom shock mounts were welded to the frame. A Biltwell seat pan was welded to the main frame with a formed tube section.
- The seat was upholstered in black leather by Devin of Uneek Upholstery. He also fit the integrated LED strip neatly in the leather.
- Hagon trail shocks, custom length
- Completely powder coated frame, forks, wheels and spokes.
- Enduralast upgraded charging system
- Rebuilt gearbox
- Shorai lithium battery in a custom made battery tray under the transmission
- TKC 80 tires front and rear
- Gas tank from a /7 R-bike, painted and pinstriped by Amanda Brisebois of Black Widow Custom Paint.
- Universal cone mufflers on stock exhaust headers, ceramic coated black.
- Custom license plate mount
- Oshmo rear sets
- Custom top triple tree with a custom bracket made out of different branches of bent rod to hold the different components. The LED headlight housing is supported with a steel ring clamped in place, mounted on the bottom. The speedometer, a Motoscope Tiny unit from Motogadget, floats on top next to mini push-button controls.
- The heart of the electrical system is controlled by the Motogadget M-unit Blue hidden underneath the tank, complete with a custom wiring harness. The m-button and associated controls wiring from the push buttons is hidden in the handlebars. The m-lock system also from Motogadget is used to activate the ignition with a key FOB.
- A set of Domino clutch and brake levers, along with a Domino quick throttle. The throttle response is improved, giving the bike a more sporty and aggressive feel. Custom throttle cables.
• Does the bike have a nickname?
RA75, since the customer’s last name is Ra. He even had a custom license plate made for the bike.
• Can you tell us what it’s like to ride this bike?
The RA75 is raw :). Seriously though, the bike was somewhat tame before customizing it, but I feel like the transformation has made it a loud and aggressive bike to ride. The free flowing pipes, combined with the tiny seat and somewhat clunky 4-speed gearbox have somehow turned a tame touring bike into a bit of an animal. It takes some care to ride, and isn’t for the inexperienced rider. The torquey and growly engine makes you want to ride like a hooligan around town, although I wouldn’t be comfortable taking it for long rides on the highway with the suitably vintage forks, and somewhat outdated braking. But for riding around the city it’s great. The bike was meant to be seen and heard, while not necessarily being ridden for long periods of time.
• Was there anything done during this build that you are particularly proud of?
This bike is probably the first one where I really started to hone in on my own style; I try to make everything as clean and simple as possible, including the shape of the metal work. With the R75, I started creating every bracket in a sort of organic style out of round stock. I bend each piece on the go and shape things in a way that works. The custom LED headlight mount — something that’s become a bit of a signature piece — came about in the same way. I wanted to push the headlight in as far as possible, and came up with a way of holding the headlight without having a bucket. Even the exhaust mounts and license plate bracket are all made out of round steel bar bent into different shapes.
I’m also proud of the electrical work and the way all the controls and accessories came together. I like how the simple push button controls, and overall classic look of the bike keeps it somehow vintage and modern at the same time.
I like to be as creative and unique as possible with what I build, but sometimes the reality of bike building is that you can be somewhat limited by budget and by the client’s specifications. Still, I’m proud of how I was able to make this bike stand out, even in a style that I think has been a little overdone.
Follow the Builder
With Emrah Gonulkirmaz: @timemachine_co | @windfaces | @gnlkrmz
Photographer, Mark Luciani: lightandgears.com | @lightandgears
Featured at the 2019 Handbuilt Show in Texas, and in the 2019 The 1 Moto Show in Portland.