Custom Works Zon Zonkern: Exclusive Builder Interview

Custom Works Zon Zonkern:
Buell-powered Custom From Japan

Teamwork can be a beautiful thing, and the partnership at Custom Works Zon provides proof of that. Working out of a modest wooden building in a rural area of the Gamou District between Kyoto and Nagoya, designer Yuichi Yoshizawa works magic with fabricator Yoshikazu Ueda.

Yoshizawa and Ueda met in high school, and have been collaborating on custom motorcycles since 1998. “We have always loved cars and motorcycles,” Yoshizawa says, “and started making custom bikes and cars ourselves because we wanted to ride something cooler than other people.”Custom Works Zon Zonkern - Buell Powered

Japanese journalist Tad Kono assists Custom Works Zon with relations with the English-speaking press, and describes the working relationship of Yoshizawa and Ueda by saying, “They have a lot of ideas for styling and lot of knowledge for metalworking and engine tuning. When creating a custom bike, they give their opinions to each other before the build, and even at halfway.”

In addition to their main roles as designer and fabricator, Yoshizawa does welding and works with machine tools, while Ueda does the crucial shaping.

Initially inspired by Californian Arlen Ness and, eventually, New Yorker Max Hazen, the Japanese pair have created some of the most stunning custom builds of the 21st century. Custom Works Zon consistently surprises with its choices. The shop is famous for Departed, its build using the BMW R 18 Project powerplant.

However, we are taken by the Buell-powered semi-eponymous Zonkern. The Zon in Custom Works Zon means ‘sun’ in Dutch—a fascinating choice for a Japanese custom shop. Zonnekern translates from Dutch into ‘core of the sun’. Finding ‘zonnekern’ to be a bit unwieldy, the motorcycle was christened Zonkern. Note that the sun makes a compelling appearance on the Zon-built fuel tank.

Custom Works Zon Zonkern - For Sale

Yoshizawa says the 1998 Buell S1 Lightning motor was chosen to power Zonkern “because the Buell engine is so powerful and sporty.” We do note that appearance wasn’t mentioned—except the beautifully adorned cases, the Keihin-carbureted air-cooled V-twin is encased in an aluminum shroud.

“A year before making Zonkern,” Yoshizawa explains, “we made a Ducati Monster S4R based machine in 2015 that covered the entire body with cowls. However, I was not satisfied with the modeling. So, I made Zonkern because I wanted to make a design that I could understand. We chose aluminum and sheet metal processing as the best way to embody the imagined image.”

The number of original pieces on Zonkern is impressive. In addition to the one-off tubular steel trellis frame—a piece Yoshizawa says was the most challenging part of the project—Custom Work Zon built the springer fork, triple clamp, single-sided steel tube swingarm, fuel tank, clip-ons, and, of course, the bodywork.Custom Works Zon Zonkern - Buell Lightning S1

As with virtually any build, there are essential parts supplied by outside companies. Michelin Scorcher 11 tires are mounted to 18-inch wheels by Performance Machine (front) and Billet Specialties. Unexpectedly, the rear tire is an unexpectedly wide 240. Brembo contributed the brake calipers and master cylinders. Backdrop Leathers in Nagoya made the seat, and the legendary Kustom Kulture artist Mr.G of Fukuoka did the painting.

More than a showpiece, Zonkern was designed for riding. “I thought I would like to make a bike that fully satisfies the basic performance such as driving, turning, and stopping, to enjoy riding the bike,” Yoshizawa says.

Fully satisfied with the result, Custom Works Zon is offering Zonkern for sale. We weren’t quoted a price, but we suspect Zonkern will be worth it.

Photography by Kazuo Matsumoto

Custom Works Zon Zonkern Photo Gallery