Source: Bike Bound
[[{“value”:”Photo: Handbuilt Show / Revival Cycles
Fast as Lightning: “One Mile” YZ125 Supermoto from Class Act Cycles…
From 1974 to the end of the two-stroke pro motocross era, the Yamaha YZ125 was a mainstay of the 125cc MX Lites class, taking home five AMA National Motocross Championships and multiple AMA Regional Supercross Championships. In 2005, the YZ125 gained a single backbone aluminum frame known to be more flickable if less stable on rough surfaces.
Though designed as a motocrosser, the two-stroke YZ has been converted to compete in flat track, supermoto, mini road races, and many other disciplines. We noticed this tracker / supermoto-style 2017 YZ125 “One Mile” build at the 2024 Handbuilt Show and had to learn more.
Soon we’d tracked down the builder, Christopher Willis of Colorado’s Class Act Cycles, who realized as a teenager that he loved fixing and modifying bikes as much as riding them.
“What started out as a hobby developed into an obsession, one that fueled the drive to open a motorcycle business and commit full-time to building, modifying, and repairing motorcycles. As a result, I opened Class Act Cycles as a full-service motorcycle shop offering a wide variety of custom work and carbon fiber parts production.”
The vision for this bike was sparked when Christopher visited IMI Motorsports Complex in Dacono, CO — a 1-mile asphalt track just north of Denver.
“I was at the track originally to rent go-karts but saw grown adults riding what looked to be their children’s dirt bikes on slick tires, racing each other around the asphalt. I thought this was the coolest thing ever, so later that day I went home and tore the YZ125 apart in preparation to convert it into something similar that could be raced around the paved track.”
Having raced our 1985 Honda XR100R at tracks like the Herrin Compound here in Georgia, we can testify to how much these small-displacement dirt bikes can be on the asphalt. While this YZ has been heavily modified for circle track racing, Christopher made sure all the changes were reversible — in fact, the bike can be reverted for dirt riding in about an hour!
“The bike was built for racing purposes and its look influenced by the simplicity of vintage Yamaha street trackers — a small fuel tank, upswept seat, number plate, and large wheels.”
Highlights include Suzuki Katana brakes and suspension (“it hasn’t been an uncommon occurrence to enter a turn on only the front wheel”), custom fiberglass seat cowl / seat / subframe designed for maximum grip and control at lean, a custom-mounted moped tank, radiators relocated forward for better turn-in, a custom steel crashbar that’s come in handy several times, and more modifications that Christopher details in our interview below.
After a few seasons of riding and racing (and even crashing), Christopher rebuilt the bike with fresh colors and paint. We love to see a functional racebike hold its own so well against the stunning array of show bikes, as well as the truly hand-built nature of the build.
Below, we talk to Christopher for more details on his “One Mile” YZ125.
YZ125 Supermoto / Tracker: Builder Interview
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
My first exposure to bikes was my father’s moped, and I have been riding classic motorcycles (Honda CB750), modern racing bikes (Suzuki GSXR), and dirt bikes since I was a teenager. I found that I love fixing and modifying motorcycles as much as riding them, and just can’t leave a bike in stock condition as I’m always thinking of ways to improve or personalize them. What started out as a hobby developed into an obsession, one that fueled the drive to open a motorcycle business and commit full-time to building, modifying, and repairing motorcycles.
As a result, I opened Class Act Cycles as a full-service motorcycle shop offering a wide variety of custom work and carbon fiber parts production.
• What’s the make, model, and year of the donor bike?
Underneath the current bike is a 2017 Yamaha YZ125 dirt bike — I made the decision that whatever modifications were done to the bike had to be reversible so that it could be ridden in the dirt again. The bike can be converted back to its stock form in about an hour.
• Why was this bike built?
This bike was built to race around a 1-mile asphalt track just north of Denver, CO. I was at the track originally to rent go-karts but saw grown adults riding what looked to be their children’s dirt bikes on slick tires, racing each other around the asphalt. I thought this was the coolest thing ever, so later that day I went home and tore the YZ125 apart in preparation to convert it into something similar that could be raced around the paved track.
The bike has been raced on the track numerous times, and even crashed and then rebuilt. After a few seasons of riding, I rebuilt the bike once again as a company promotional piece — fresh paint, decals and fun colors!
• What was the design concept and what influenced the build?
The bike was built for racing purposes and its look influenced by the simplicity of vintage Yamaha street trackers — a small fuel tank, upswept seat, number plate, and large wheels. The contour lines of the fuel tank influenced the shape the seat cowl was built to take and the rest of the build followed suit.
The idea behind the lightning bolt paint theme originated after riding the bike around the track one day and thinking, ‘this is as fast as lightning!’.
• What custom work was done to the bike?
The frame, engine and rear end are originally from a Yamaha YZ125 dirt bike — the rest has been pieced together from other bikes or built by hand.
The custom-mounted fuel tank is from a 2-stroke moped, the custom rear seat cowl built out of fiberglass, and subframe built to support the seat and rider.
The radiators were relocated forward, leaving room for the tank to be installed on the frame and also to bring weight forward on the bike, allowing for better turn-in capabilities.
Included in the frame work is a custom steel crash bar which has worked wonders when protecting vital engine components during drops and crashes. The paint, and especially the bright yellow accents, was added to enhance the visual appeal.
• Does the bike have a nickname?
The build was dubbed the “One Mile” — named after the length of track it was built to race on.
• Any idea of horsepower, weight, and/or performance numbers?
Performance-wise the bike remains mostly stock from the factory, although removing part of the airbox and shortening the overall length of the exhaust has resulted in noticeable performance gains, relative to a stock one-cylinder two-stroke 125cc dirt bike.
• Can you tell us what it’s like to ride this bike?
Riding this bike reminds you that you are on it for one purpose only — to race. The gearing has been set up to allow for the most torque coming out of tight corners in order to pass riders and the 125cc engine offers plenty of power to make this happen.
Utilizing brakes and suspension from a Suzuki sport-bike allows for superior stopping power and it hasn’t been an uncommon occurrence to enter a turn on only the front wheel. Care was spent in the design of the seat to create maximum grip and control while leaned over at high speeds.
• Was there anything done during this build that you are particularly proud of?
I built the fiberglass rear seat cowl from a mold that originated as a piece of flat sheet metal. The sheet metal was bent using a handmade metal-bending brake built from whatever materials were laying around the shop at the time.
Many of the other parts on the bike follow the same theme, as they were built from otherwise unused materials found around the shop. Overall I’m proud of having been able to piece the bike together through both fabrication, and the adaptation of existing parts that wouldn’t normally be combined in the way I did. I’m especially happy with the way the jigsaw puzzle ended up coming together in a coherent, unified way.
• Is there anyone you’d like to thank?
We’d like to thank Revival Cycles for including the build at The Handbuilt Motorcycle Show 2024 in Austin, TX and IMI Motorsports Complex in Dacono, CO for offering year-round track riding.
Build Sheet
Warp9 Racing rear supermoto wheel
Suzuki Katana front mag wheel & front end
Suspension tuned for track
Racing slicks
Custom crash bar
Radiators relocated, custom mounts
Custom fiberglass rear racing cowl, subframe
Moped fuel tank, custom mounts
Follow the Builder
Web: classactcycles.com
Instagram: @classactcycles.co
Facebook.com/classactcycles”}]]
