FZ-Inspired XSR900 from Crazy Garage…
Chi-hyun Kim of South Korea’s Crazy Garage focuses on custom bikes that don’t just look good parked in the paddock or at the local cafe, but perform well on the track and in the twisties:
“The concept of the shop is mainly that of making bikes that can be enjoyed on the race circuit or winding roads… I enjoy riding on the circuit with custom bikes…”
Back in 2018, we featured Crazy Garage’s 883 Sportster street tracker built for road racing at Korea International Circuit (KIC) about 400 kilometers south of Seoul.
A year later, Kim introduced us to his BMW S1000RR “Retro Racer” — a modern superbike built for a customer who wanted a high-performance track weapon with the outward appearance of an 80s endurance racer.
Now we’re thrilled to feature Crazy Garage’s first build of 2024, the Yamaha “X-FZ900” you see here — a Yamaha XSR900 transformed into a track bike inspired by the iconic FZ750 of the 1980s.
The XSR900 is Yamaha’s 117-hp, three-cylinder naked retro bike based off of the MT-09. In factory trim, the XSR recalls the Yamaha FZ and YPVS models of the 1980s.
“A fantastic road bike with a brilliant engine. There’s more than enough power and torque for the road, backed up by excellent rider aids and chassis.” –MCN
The XSR900 engine is Yamaha’s CP3 inline-triple, a liquid-cooled 849-890cc crossplane design that riders and reviewers have come to love.
“With this arrangement, there is zero shaking of the engine’s center of mass and zero crankshaft rpm flutter caused by piston inertia torque. But there is a side-to-side rocking…canceled by a crank-speed balance shaft.” -Kevin Cameron, Cycle World
However, Kim and his client wanted to transform this XSR into a more direct descendant of the FZ750 — one built for the track.
“I love the 80s-style bikes with half fairings like our S1000RR that was featured a few years ago. I planned a project with the owner to make the XSR900 a bike for the track and I wanted to make it a model with Yamaha’s heritage. So what I chose was the FZ750, which was equipped with Yamaha’s first Genesis philosophy. I wanted to preserve the silhouette of the FZ750…”
Introduced in 1985, the FZ750 was designed to replace Yamaha’s highly successful two-stroke sport and race bikes. The design brief called for an engine that would develop at least as much power as the two-stroke TZ750 in race trim, and the FZ750 was the first to feature Yamaha’s Genesis engine, featuring 5 valves per cylinder. Soon Genesis would be come an entire design concept focused on the integration of engine, chassis, and rider.
“Aiming for a harmonious oneness between rider and machine, design concepts based on Genesis have been a constant presence in Yamaha’s subsequent motorcycle development activities.” –Yamaha Motor Corp.
Kim used the front fairing and tank cover from an actual FZ750, fabricating the fairing and instrument panel brackets out of aluminum.
A one-off aluminum subframe was welded up with a custom 11-liter inner tank whose shape is designed to maximize the efficiency of the DNA Stage 2 air filters. Kim says the aluminum subframe weighs than less than half that of the original one.
For the rear cowl, Kim wanted to create a real racer look, so he modified the FRP (fiber-reinforced plastic) single seat of the FZR series. The exhaust consists of an Arrow header with an original mid-pipe and old-school silencer.
Since this is a bike built for use on the actual track, the ECU has been remapped to match the changed intake and exhaust parts. The radiator is an R6 unit that Kim modified to increase coolant capacity for long sessions at high rpm.
Of course, besides tire choice, nothing on the track is more important than suspension, so Kim went with the best. The X-FZ is now running Öhlins front cartridges and rear shock.
The bellypan was made from scratch, not ready-made, and both FRP and carbon were used throughout the build.
As you might expect, this “X-FZ900” is much lighter and tighter than the original.
“The current wet weight is in the high 150-kg [~350-lb] range, which is lighter than the Ninja 400. Once we upgrade to lightweight wheels, it is expected to weigh in the mid 150-kg range.”
Given that the stock XSR weighs 193 kilograms (426 pounds), that’s a weight decrease of some 75 pounds already!
We can’t wait to see this FZ-inspired XSR ripping around the South Korean race tracks this summer. Thanks again to Chi-hyun Kim for sharing the build and Brother Photography for the shots.
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Photography Credit: @brotherphotography_kr
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