Speed Read, April 2, 2023

The latest motorcycle news and customs
A modern Kawasaki Z900RS gets the AC Sanctuary treatment this week, followed by a wild Yamaha RD400 street tracker. On the back half of our round-up; a Triumph Street Twin prepped for flat track racing, and a twin-turbo BMW R100 destined for a museum.

Custom Kawasaki Z900RS by AC Sanctuary
Kawasaki Z900RS by AC Sanctuary Out for a few years now, the Kawasaki Z900RS is a modern classic that riffs off the nostalgia of Kawasaki’s 70s era—specifically, the iconic Z1. It’s a solid effort from Big Green, but, like many modern motorcycles, there isn’t a whole lot of room for customization. Unless you’re AC Sanctuary, of course.

The Japanese powerhouse never fails to impress with their hopped-up classic big four Kawasaki restomods. They’ve built almost 600 bikes as part of their ‘RCM’ (‘Radical Construction Manufacture’) series already. But this is the first time they’ve applied the RCM philosophy to the Kawasaki Z900RS.

Custom Kawasaki Z900RS by AC Sanctuary
From a distance, RCM-534 doesn’t look too dissimilar from a stock Z900RS, albeit with an extremely high-end paint job. But AC Sanctuary’s genius becomes more apparent the closer you get.

For starters, the Kawasaki’s steel trellis frame has been augmented with something it didn’t have before—lower frame rails, added to improve the chassis’ rigidity. There’s also reinforcement at the swingarm pivot, and a widened aluminum swingarm. And the good news for customizers, is that these particular mods will be made available in kit form.

Custom Kawasaki Z900RS by AC Sanctuary
The Z900RS also sports Öhlins suspension at both ends, gorgeous OZ Racing wheels, Brembo brake calipers and Sunstar discs.

The engine remains stock inside (it’s no slouch), but it’s been treated to a high-performing aluminum radiator, and a titanium four-into-one exhaust from Nitro. And if you’re ordering your own Z900RS-based RCM, AC Sanctuary can spec it with a row of Mikuni carbs too, if you’d like.

Custom Kawasaki Z900RS by AC Sanctuary
Smaller mods include a custom rear brake caliper bracket, upgraded risers, bars and levers, CNC-machined headlight ears and a fender delete kit. As for the aforementioned paint job, it’s a subtle hat-tip to the Z1 of old. [Via]

Yamaha RD400 street tracker by Gaston Motorcycle Werks
Yamaha RD400 by Gaston Motorcycle Werks Sifting through the boxes at an estate sale some time ago, the team at Gaston Motorcycle Werks struck pay dirt. The woman holding the sale had just lost her husband, and among the crates were the bits and pieces of a Yamaha RD400. More specifically, a coveted 1979 Yamaha RD400F Daytona.

The team intended to restore it to its former glory, but didn’t quite get around to it. Then the perfect customer for it came along—and what started out as a tidy restomod became a full-blown custom street tracker.

Yamaha RD400 street tracker by Gaston Motorcycle Werks
There’s a lot to take in here. One of the big ideas was to ditch the RD400’s classic twin-shock rear suspension. So GMW adapted a 1980s Yamaha RD250LC swingarm to the bike, then fabricated a new subframe and upper shock mount.

The front forks are Ceriani GP replicas, held in place by custom yokes and aided by a steering damper. The wheels feature Borrani rims and drum brake hubs; the four leading-shoe Robinson twin brake unit on the front is particularly drool-worthy.

Yamaha RD400 street tracker by Gaston Motorcycle Werks
The engine’s been treated to a crank rebuild by HVC Cycles, new Wiseco pistons, Lectron carbs and more. Then there’s the stainless steel Jim Lomas exhaust system, terminating in twin carbon fiber mufflers. (Seriously, pause for a moment to take it in.)

Dressed in flat track garb, with wide bars to match, the RD400 is finished off with a simple grey and blue palette. With lights and a cleverly-integrated Motogadget speedo, this zesty two-stroke probably isn’t destined for the track. And that’s perfectly fine with us; we can’t think of a better whip to hop from café to café on. [Via]

Triumph Street Twin hooligan flat track racer by British Customs
Triumph Street Twin by British Customs I’ve just put a pre-owned Triumph Bonneville in my garage—so, naturally, I’ve been scouring cyberspace for parts. And no British twin parts expedition would be complete, without a visit to British Customs’ online store.

Trawling their archives, I came across this Triumph Street Twin. Built a few years ago, it belongs to 2000 AMA Pro Flat Track champion Joe Kopp, who modified it to run in the American Super Hooligan flat track race series.

Triumph Street Twin hooligan flat track racer by British Customs
The twin-cylinder modern classic wears British Customs’ bolt-on ‘Slammer’ seat, with a set of high-mounted twin exhausts modified to run on the right. It rolls on 19” wheels, with a set of Fox shocks propping up the rear. The fuel tank is stock, but the headlight’s been ditched in favor of a number board.

Up in the cockpit, Joe fitted British Customs’ ‘Tracker’ handlebar kit, complete with risers that sport four bolts per side. He modified the controls too, but had to leave the speedo connected, or else the bike wouldn’t run. A handful of smaller add-ons round out the build, like Bates-style pegs, a drilled chain guard and a finned clutch badge.

Triumph Street Twin hooligan flat track racer by British Customs
As Triumph flat trackers go, we’ve seen wilder. But what makes this build so charming, is its grassroots vibe. By taking a bone stock Street Twin and throwing a bunch of function-first, race-specific mods at it, Joe and British Customs have encapsulated the ‘run what ya’ brung’ nature of hooligan flat track racing.

But is it competitive? Sure is. From what we can dig up, Joe damn near won the championship in the year that he fielded the Street Twin. [More]

Turbo-charged BMW R100 by Boxer Metal
Sold: twin turbo BMW R100 by Boxer Metal Long time custom bike fans should recognize this gold-hued boxer. Built by Boxer Metal in California, it broke the internet when it first popped up seven years ago. And it’s just sold on Bring a Trailer, for the tidy sum of $23,500.

Turbo-charged BMW R100 by Boxer Metal
Run by the husband and wife team of Chris and Rebecca Canterbury, Boxer Metal originally built the BMW R100 to enter it into the One Show in Portland. It’s a knockout build—the highlight of which is undoubtedly the two turbo chargers that encapsulate the boxer engine.

The mods are endless. There’s the countless pieces that make up the turbo system run, plus the stretched and slammed hardtail frame. It rolls on a 21” spoked front wheel and a modified 18” Lester alloy rear wheel, with a M&H Racemaster drag slick doing duty out back.

Turbo-charged BMW R100 by Boxer Metal
A Dnepr fuel tanks sits up top, finished in an unforgettable gold metal-flake paint. The custom-made leather seat sits atop a one-piece seat pan and rear fender. Boost gauges are embedded into the back of the fuel tank, just in front of the rider’s groin. It’s a stunning machine, no doubt.

But the most notable detail, is where the bike’s headed. After a week of bidding, the BAT user Seriousvintagecollector came out on top. A glance at his profile reveals that he’s recently snapped up a 1959 BMW R26, a 1962 BMW R27, a 1964 BMW R69S, two 1967 BMW R60/2s, a handful of 1970s R-series BMWs and more.

Turbo-charged BMW R100 by Boxer Metal
Highlights of his current collection include a 1936 NSU 601 with a Royal Seitenwagen sidecar, and a 1957 BMW Isetta 300 that cost him a cool $50,000. He’s more than just a passionate collector though—once he’s amassed enough vehicles, he’s planning to open a museum, either in Georgia or South Miami.

By the looks of things, he’s off to a cracking start. [Boxer Metal]

Turbo-charged BMW R100 by Boxer Metal

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