Custom Works Zon have a stellar reputation in their home country of Japan, but are only just becoming known outside. Six months ago, BMW propelled Zon into the limelight when they revealed the R18 ‘Departed’ collaboration at the Mooneyes show—and now Zon are back with an equally amazing Buell S1 Lightning custom.
It’s called ‘Zonkern’—which means ‘core of the sun.’ And almost everything on this V-twin, aside from the engine, has been fabricated by hand.

It’s an extreme build, but by Zon’s standards, it’s fairly practical. In Japan, builders Yuichi Yoshizawa and Yoshikazu Ueda are known for their outrageous show bikes—including one with a hub steering system built for a Michael Lichter show—and others with unfeasibly large wheels.
This time, Yuichi and Yoshikazu have toned things down a little. “We wanted to make a bike that satisfies basic performance duties, such as turning and stopping, while being enjoyable to ride,” Yuichi tells us.

Zon considered using a Japanese bike as a base, but decided to stick with the Harley-Davidson engine that they’re most familiar with: “If you’re speaking about a sporty engine with good response, there’s only Buell.”
They located a 1998 S1 Lightning. Or rather, parts of one: the engine and frame.

The engine, quite frankly, is the best part of the S1. The 1200cc Sportster unit used in the Lightning only delivers 86 hp at 6,000 rpm, but offers a meaty 78 lbs ft of torque a few hundred rpms lower down the range. Zon have plumbed in a pair of Keihin FCR carbs though, which should lift power a little—and push quarter mile times under the 12-second mark.
The S1 series used a steel tubular frame, rather than the famous aluminum XB-type frame of its successor. Unlike the XB frame, the steel frame didn’t particularly benefit handling,

So Yuichi and Yoshikazu have built a new trellis-style frame from scratch, using the lessons they learned while revamping a Ducati Monster in 2015. They also took the opportunity to make the custom frame as compact as possible, to give them extra freedom with the amazing hand-beaten bodywork.
“I wanted a frame that was small and light, and with good agility,” says Yuichi. “The goal was achieved, but it’s not a frame that should be visible on a custom bike. I pursued only the function.”

Fabricating a complete new frame is hard enough, but Zon have gone one step further and installed a shrouded springer-type front end. And the springer setup isn’t an off-the-shelf Harley part: it’s their own design, complete with custom triples, a hand-made steering stem, and one-off clip-ons.
Zon also built the single-sided swingarm, configured for a monoshock suspension setup.

The wheels are 18 inches front and rear, with Performance Machine supplying the front rim and Billet Specialties delivering a monster 8.5-inch wide rear hoop. Zon have installed Michelin Scorcher 11 tires, in a whopping 240 section at the back.
The brake system is Brembo all round, with two-pot calipers, and the foot controls are a blend of Zon and LSL parts.

Yuichi freely admits that the hardest part of the build was the aluminum bodywork, though. It’s a masterpiece of metalwork, with a completely enclosed front end, and a 1950s sci-fi vibe—reminiscent of the work of artists like Frank Kelly Freas.
It looks raw and mechanical in the best possible way, with pinstriped silver flames painted on the flanks by local artist Mr G.

The seat (and the matching highlights just below on either side) is by Back Drop, a leather specialist also based on the main Japanese island of Honshu. It’s a classic tuck and roll pattern, adding to the timeless vibe of the S1.
Craftsmanship at this level takes a huge amount of time and skill, but the Buell was not a commission—it’s purely an in-house build designed to showcase the abilities of Custom Works Zon.

That’s what you call a leap of faith, but if this Lightning generates a surge of interest in CW Zon in the West, it’s a gamble sure to pay off.
Custom Works Zon | Facebook | Instagram | Images by Kazuo Matsumoto | Thanks to Tadashi Kono