For Sale: 700cc, 277-Rephased “Xcess” from Marty Coblentz…
In the 1950s, Britain built one out of every four motorcycles globally. However, as the Japanese rapidly advanced into the big bike market, employing modern tooling and designs, the historic British marques were faltering. Triumph, Norton, and BSA all went under in the 1970s, and they wouldn’t be reborn for years.
Fortunately, Yamaha stepped in to build “the modern twin the British never built” in the form of the XS650. Here was a bike that preserved the design and character of the great British twins, but with unit construction, a horizontally split crankcase, and modern oil-tightness and reliability. The XS was destined to become one of the most beloved Japanese motorcycles of the era, and today it still enjoys a diehard following.
This ’77 XS650 café racer comes from Marty Coblentz of Wellington, Nevada, who had quite an early (and audacious) beginning as a custom bike builder:
“I’ve been into two wheel projects since age 13 when I ‘borrowed’ the engine from my Dad’s lawnmower to complete a mini bike project. The installation was successful but the engine was returned to the mower once he discovered it missing.”
Fortunately, Marty’s father forgave his son’s two-wheeled transgressions before his passing, and Marty would go on to own several iconic British machines, among them a 1967 Triumph TR6C, 1967 Norton Dunstall 750, and a BSA Goldstar. He also pursued fabrication and welding as both a hobby and profession.
When he decided to build a custom bike he “could actually ride,” the XS650 was his twin of choice.
“I wanted to build a café bike with modern suspension and brakes around a vintage parallel twin.”
Marty was especially interested in the work of Hugh at Hugh’s HandBuilt of Asheville, NC, who’s well-known for re-phasing XS engines to a 277-degree firing order, rebuilding your original crank and camshaft in-house.
“We rebuild the crank from the middle out. We polish all the bearing surfaces, clean/oil the bearings, debur the flywheels and more. We build these cranks for performance, and each pressed joint is trued and TIG welded* (for high RPM durability) as we build the crank. Once the rods and outer flywheels are installed, the crank is fully trued in our fixures and given a final rod pin TIG weld to each end for the ultimate in reliability and performance. The crank is then ready to bolt in just like OEM.” -Hugh
According to Marty, the 277 rephase makes quite the difference from the stock 360-degree crank.
“The 277 degree firing order significantly reduces vibration and it sounds bitchen too. Seems to pull better from lower RPM as well.” -Marty
Marty also went with a Shell #1 cam, 700cc JE pistons, Mikuni VM34 carbs, PMA alternator, Pamco electronic ignition, and even a 5th gear overdrive — trick!
But the engine was just one part of the puzzle. To bring the handling and braking up to more modern standards, Marty swapped in a set of GSX-R750 forks and brakes, matched with a Cognito Moto front hub and EBC rotors. Out back there’s a mono-shock conversion with a braced Yamaha Radian swingarm and Öhlins rear shock. The rear hub and brake are from a Suzuki DR650, and the bike is rolling on Sun rims with Buchanan spokes.
“The seat pad is thin so when you need to stop for fuel, your butt will thank you. It’s great for fast trips in the twisties. Definitely not a long distance cruiser…”
“Anyone who builds one off custom bikes knows that solving the inevitable problems that crop up in pursuit of ‘The Vision’ makes the finished project all that much more rewarding. I am proud of the fact that the finished project matched the vision I had when I started and I was able to overcome the issues that arose. There is a myriad of custom details that will escape the eye unless you look closely…”
Bravo, Marty, for transforming your dream into a fire-breathing reality we’d love to ride. Below is our full interview with the man himself about the build, and stay tuned for another custom Yamaha from this Nevada-based builder.
Yamaha XS650 Café: Builder Interview
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
I’ve been into two wheel projects since age 13 when I “borrowed” the engine from my Dad’s lawnmower to complete a mini bike project. The installation was successful but the engine was returned to the mower once he discovered it missing.
I raced motocross in the 250cc and open class as a teen until a knee injury ended that dream. I’ve owned numerous British parallel twins and singles (’67 Triumph TR6C, ’67 Norton Dunstall 750, BSA Goldstar) while growing up, and when I decided to build a custom bike I could actually ride, the XS was my choice (being the modern twin the British never built).
I’ve been into welding and fabrication since high school as both a profession and hobby. I have a modest shop with the necessary equipment to allow me to machine or fabricate one off parts for my projects.
• What’s the make, model, and year of the donor bike?
The bike started life as a 1977 Yamaha XS650.
• Why was this bike built?
I wanted to build a café bike with modern suspension and brakes around a vintage parallel twin.
• What was the design concept and what influenced the build?
I was looking to build something that would challenge my abilities and problem-solving skills. I wanted something that looked different from other café projects and that would handle well and be fun to ride.
I was also intrigued by the work that Hugh at Hugh’s Handbuilt had achieved with re-phasing the XS motors. The 277 degree firing order significantly reduces vibration and it sounds bitchen too. Seems to pull better from lower RPM as well.
• What custom work was done to the bike?
• Does the bike have a nickname?
Xcess.
• Any idea of horsepower, weight, and/or performance numbers?
The bike has never been on a dyno but with the engine mods, I’m guessing somewhere between 65 and 70HP. The bike weighs 381 pounds wet.
• Can you tell us what it’s like to ride this bike?
Modern suspension and brakes make it fun to ride. It handles well and inspires confidence when pushed hard. The bike is not blisteringly fast but pulls well from the bottom and has a fairly wide power band.
The small (2.2 US Gal.) fuel tank definitely limits the range, but the seat pad is thin so when you need to stop for fuel, your butt will thank you. It’s great for fast trips in the twisties. Definitely not a long distance cruiser…
• Was there anything done during this build that you are particularly proud of?
Anyone who builds one off custom bikes knows that solving the inevitable problems that crop up in pursuit of “The Vision” makes the finished project all that much more rewarding.
I am proud of the fact that the finished project matched the vision I had when I started and I was able to overcome the issues that arose. There is a myriad of custom details that will escape the eye unless you look closely.
The seat/tail fabrication (photo that looks like a Peruvian mask!) took a lot of time as I did not have a brake so all the pieces were cut on the bandsaw and welded together. I was happy with the result.
• Is there anyone you’d like to thank?
Zane at RaceTech was invaluable in helping me with the rear suspension geometry. Kyle from World Class Hot Rods is credited with the paint and airbrush work.
