Since the dawn of Grand Prix motorcycle racing, the 125 cc class has served as a proving ground for factories and riders alike, producing frenetic racing and memorable machines. The 250 cc Moto3 class replaced the classic 125 cc category twelve years ago, but Grand Prix racing’s ‘starter’ series continues to provide thrills—and glimpses of future MotoGP superstars.
This SYM Wolf 125 pays homage to the golden age of 125 cc GP racing. It’s the work of Eric Ku—a Taiwanese custom motorcycle builder who works under the moniker of FirstRider Custom and loves vintage race bikes.
“I have a strong passion for 1960s racing, particularly as a Honda enthusiast,” he tells us. “I aspired to create my own vintage racing motorcycle, visualizing myself speeding down the track. I also fantasized about what designs I would have implemented as a designer back then to help racers win championships.”
In stock form, the SYM Wolf 125 is a humble commuter—albeit an immensely popular one in its home country. But Eric’s Wolf is unrecognizable. Undertaking every task himself, save for the paint job, he went to great lengths to transform the bike into a modern take on iconic classics like the Honda RC143.
“The overall design takes cues from Honda’s RC series,” Eric confirms. “I adjusted the body proportions to fit my physique, including legroom and chin clearance. The tail section incorporates some modern elements similar to the fixed-wing structures seen in today’s MotoGP bikes, blending vintage and modern aesthetics.”
Working from the inside out, Eric bored the Wolf’s 56.5mm cylinder out to 67 mm, stuck a bigger piston in there, and fabricated a custom crankshaft with a longer stroke. That took the motor up to approximately 247 cc, with a five-speed transmission replacing the OEM four-speed box. A reinforced clutch and an upgraded oil cooler were added to maintain performance and reliability.
Eric also replaced the cylinder head with a modified unit that has two exhaust ports. It now uses bigger intake and exhaust valves, with a Keihin PWK36 carb mounted on a custom-made alloy intake that orientates it sideways, since that’s the only way it would fit. “I crafted a direct-intake port, which not only enhanced performance, but also created a visually striking impact on the overall appearance,” Eric adds.
The carb sucks air through a chunky velocity stack that pokes through the bike’s fairing. Gasses exit via an asymmetrical twin exhaust system. One of the mufflers emerges from the bodywork up high on the left, while the other runs along the bottom of the bike on the right.
The SYM’s fairing and fuel tank are loose recreations of the Honda RC143’s bodywork. Eric not only shaped the fiberglass fairing by hand, but even went as far as creating his own acrylic windscreen—a challenging process with several failed attempts. A simple rectangular headlight sits behind a protective grill up front.
Low-slung clip-ons sit behind the fairing, fitted with pared-down controls and white vintage-style grips. One particularly neat touch is how the custom fairing stays are integrated with the speedo housing.
The steel tail section follows a less traditional design. Featuring a scalloped design with deep grooves, it flows tightly into a finned 3D-printed taillight. Lower down, an open battery tray offers a rough-hewn race bike vibe, while still keeping everything tidy.
Under the bodywork, Eric liberated the frame of all superfluous mounting tabs, before welding in extensions to place the footpegs in an optimal position. The bike now rolls on 18” DID rims, with a modified Yamaha SR150 drum brake hub at the front. (Eric’s handmade front brake air scoop is yet another attractive detail.)
Eric chose blue and white for his SYM Wolf racer’s livery, not because of any particular historic motorcycle, but because those are his favorite colors. The combo suits this bike perfectly, with white finishes on the frame and forks to set it off.
But perhaps this project’s biggest success is how well it encapsulates the era that inspired it. If we didn’t know any better, we’d think that the photos of Eric riding his Wolf on the track were taken in the 60s.
