Down the Rabbit Hole: Dwight Mason’s 1990 GSX-R750 Custom…
In 1985, the original GSX-R750 revolutionized the world of sporting motorcycles, setting the superbike standard for years to come. The old heavy steel frames and comfortable ergonomics were out, replaced with aluminum chassis, racetrack geometry, and uncompromising performance. The GSX-R was the closest thing to a roadgoing racebike ever available in mass quantities, and it would quickly become one of the most-raced production bikes of all time.
In 1988, the original “Slabbies” or “Slabsides” were replaced with the second-generation “Slingshot” models, so-named for their semi flat-slide “slingshot” carbs. The 1990 GSX-R750 was the best of the lot, featuring inverted forks, a long-stroke oil-cooled motor with lighter pistons, and a potent 115 bhp on tap.
“There is one corner of our sport were compromise is all but nonexistent, and that corner is ruled by bikes like the 1990 Suzuki GSX-R750. The GSX-R was built with two purposes in mind: to go fast, very fast, on twisty roads, and-with slight modifications-to go faster yet on racecourses” –Cycle World, 1990
Earlier this month at the 2024 Handbuilt Motorcycle Show, this highly modified 1990 GSX-R750 “Cafe Gixxer” instantly caught our attention with its streamlined, purpose-built endurance look, showcasing that mighty, many-finned brute of an engine. We set out to track down the builder, Dwight Mason, whose love for cafe racers can be traced back to his very first bike, a Vulcan 500 which he completely transformed in his parents’ garage with limited tools and skills. Today he works on nights and weekends out of his own two-car garage, stocked with the tools and materials he’s accrued over the years.
“Motorcycles are my hobby, my cheap therapy, and a way for me to recharge my mental batteries after long days at an architecture office.”
He considers the “Cafe Gixxer” (he’s not entirely keen on the nickname but has made his peace with it) his first real build, and it takes inspiration from cafe racers, retro endurance racers of the ’80s and ’90s, and even the Ducati Sport Classic.
Dwight gives us the full rundown of the modifications in our interview below. We’re especially impressed with some of the more creative solutions he came up with, including the brackets he designed to hold the hand-cut and manually-bent steel subframe and the Pepakura software he used to create the mold for the half fairing:
“Pepakura is often used in the cosplay world for taking models of things like armor and helmets and ‘unfolding’ the geometry into a flat surface that can be cut from any flat material (usually paper or eva foam) and folded back into the 3D shape. I cut my unfolded model from chipboard using a laser cutter, folded and glued it into its 3D form, then fiberglassed over it.”
We love the stripped-down hot rod look of the finished bike, and the ride is just as visceral:
“It’s loud, it feels raw, you get a tactile connection with the road… It’s not as fast as a modern sport bike, but it’s still fast—fast enough to get me into trouble.”
The combination of homespun ingenuity and manual elbow grease perfectly aligns with the manual ethos of the Handbuilt Show, and we’re excited to see what’s to come from Dwight Mason Designs:
“With a new sense of direction I’m ready to continue my motorcycle building adventure and see how deep this rabbit hole goes.”
Below, we talk to Dwight himself for more details on himself, his shop, and the build. Enjoy!
GSX-R750 Slingshot Custom: Builder Interview
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
I started riding in 2006 when on a whim, I got my motorcycle license and went and bought a brand new Kawasaki Vulcan 500. I rode that bike as a daily driver for most of my college career.
Sometime in the first couple years of owning that bike, I learned about cafe racers and I was hooked! I immediately tore the Vulcan 500 down and built a cafe racer of my own. Not an ideal candidate for a cafe racer, but I didn’t care—I wanted one and I wasn’t afraid to chop up some metal and try my hand at fabrication despite working out of my parents’ garage with very few tools.
Fast forward to today: My workshop is a two-car garage conveniently attached to my house—it is a culmination of tools and materials I have acquired over the years. Motorcycles are my hobby, my cheap therapy, and a way for me to recharge my mental batteries after long days at an architecture office.
Even though I’ve technically built two other bikes before the GSX-R, I consider the GSX-R my first real build—a build I’m proud of. I now have two other project bikes ready for some attention. With a new sense of direction I’m ready to continue my motorcycle building adventure and see how deep this rabbit hole goes.
• What’s the make, model, and year of the donor bike?
1990 Suzuki GSX-R750.
• Why was this bike built?
This was a personal project.
• What was the design concept and what influenced the build?
I’ve been captivated by cafe racers for the majority of my time with motorcycles. I’ve also been really drawn to retro race bikes. I was also quite inspired by the Ducati Sport Classic. I took some styling inspiration from the Ducati cafe seat cowl but modified the design a bit—I thought the shape played well with the curvature of the GSX-R fuel tank.
Retro endurance racers were also heavily inspiring for my build. I opted for the half fairing look reminiscent of 80’s and 90’s era endurance race bikes.
• What custom work was done to the bike?
I hand carved foam board and fiberglassed over it for the seat/rear cowl. Holding the seat/cowl is a custom hand-cut and welded tube steel subframe. I made all the cuts and bends with an angle grinder and manual tube bender. My buddy with many more hours of welding under his belt than me TIG welded all the tubing together.
For the tail light, I didn’t want to labor over a steel pocket cut and welded into the tail hoop, so I designed and 3D printed an insert that fits into a slot cut into the tube and bolts in from the back side. The slimline LED nestled nicely in the 3D-printed insert and the wires were hidden in subframe tube.
The original subframe was welded to the main aluminum frame and didn’t fit the look I was going for, so I cut it off. I’m sure there are plenty of purists out there cringing at the idea of me cutting up a rare 90s GSXR frame, but I made up my mind and went for it.
Since welding aluminum wasn’t in my arsenal, I had to devise a way to mount the subframe to the original frame. I designed a bracket solution that bolts to the cross members of the original frame and captures the mounting tubes of my subframe design. This produced a rather nice floating appearance as the mounting tubes didn’t directly touch the side profile of the original frame.
The same construction approach was applied to the frame holding the nose fairing. I just eye-balled a handful of ½” tube steel cuts and bends, then my buddy welded it all together. The nose fairing held by this frame was also constructed in fiberglass but with a twist… I designed and modeled the nose fairing in 3D then exported the model to a software called Pepakura.
Pepakura is often used in the cosplay world for taking models of things like armor and helmets and “unfolding” the geometry into a flat surface that can be cut from any flat material (usually paper or eva foam) and folded back into the 3D shape. I cut my unfolded model from chipboard using a laser cutter, folded and glued it into its 3D form, then fiberglassed over it.
Of course there was a good deal of body filler required to get it looking smooth, but I like to call this part a functional prototype. In the future I may use it to produce a mold for fabricating a proper nose fairing.
“Under-the-hood” or under the seat in this case, are the electronics powering the GSX-R. I rebuilt the entire wiring system from scratch—using an NWT X21 Plus to run the circuits (similar device to MotoGadget’s M-Unit), a Dyna 2000 ignition system, and new Dyna ignition coils. Powering the setup is an ultra light and small Lithium Ferrous Phosphate (LiFePO4) battery from NWT Cycletronic.
• Does the bike have a nickname?
I had to provide a nickname to enter it to the Hand Built Show. While not entirely keen on the one I went with, I’ve made my peace with it: “Cafe Gixxer.”
• Any idea of horsepower, weight, and/or performance numbers?
I haven’t done any performance testing yet, but I imagine with the weight reduction and carb tuning, I’ve acquired at least a couple more ponies and a bit more acceleration potential.
• Can you tell us what it’s like to ride this bike?
Riding this bike is, in my opinion, a fantastic experience. It’s loud, it feels raw, you get a tactile connection with the road, I almost feel like I belong in a Mad Max movie when I’m cruising down the road even though the bike looks more like it belongs in the movie 2001: A Space Odyssey. It’s not as fast as a modern sport bike, but it’s still fast—fast enough to get me into trouble.
• Was there anything done during this build that you are particularly proud of?
I’m quite proud of the subframe and nose fairing frame designs. I honestly didn’t put a whole lot of thought into those parts. I just started cutting and bending steel and holding them to the bike to see if it looked right. I was quite pleased with the results.
• Is there anyone you’d like to thank?
My buddy Nick Miracle deserves a huge thanks for his time and effort. Many late nights were spent in my garage burning metal. I know he appreciates the welding practice, but still, I can’t thank him enough.
Additionally, and more importantly (sorry Nick), but my wife deserves a medal for being such a staunch supporter of my passion. She is my favorite person in the world and I don’t know what I did to deserve her.
I’d also like to thank David at NWT Cycletronic. David is the owner and lead engineer at NWT. His idea for how a motorcycle company should operate is phenomenal. They are dedicated to their customers—providing live support and an unprecedented warranty for their products. David helped me troubleshoot some electrical problems I was having with my build and he got me up and running.
Follow the Builder
Web: www.dwightmasondesigns.com
Instagram: @dwightmasondesigns
Thanks: @nick_miracle | @nwtcycletronic
Just my opinion but I think the original stock bike looks way bettter.
Yeah it was a real beauty 🤣
Great article on a tasteful and practice build. I enjoy these bikes built by regular enthusiasts with patience and ingenuity much more than some un-rideable wet dream dripping with expensive parts. Great lines and proportions on this.