Established by Masashuiko Waiku back in 2001, Bull Dock is one of the most prolific workshops of its kind in a country teeming with such firms. We are, of course, talking about Japan – the home of anime, sushi, and some of the raddest custom motorcycles you will ever come across. Parts fabrication, regular maintenance, and restorations are all part of Bull Dock’s repertoire, but we’re here to talk about their fully-fledged one-offs.
They refer to each of these as a GT-M, which stands for Genuine Tuning Machine. The specimen pictured above was developed by Waiku-san's experts in collaboration with Nitron – the UK-based aftermarket suspension brand. Nitron’s Japanese branch commissioned this build with the intent of showcasing their products, and Bull Dock clearly delivered in a big way!
Some may shudder at the idea that an iconic Kawasaki Z1-R was irreversibly modified in the process, but we’re actually not mad at all. Bull Dock’s bike-modding connoisseurs transformed the 1978-model Kawi into something more suitable for today’s roads, from both a cosmetic and mechanical standpoint. Oh, and there’s a lot more to it than just visual appeal and top-tier suspension, so we’ve got quite a bit to cover here.
After a complete teardown, the GT-M treatment began with some intricate frame surgery. Masashuiko and his crew reinforced the Z1-R's skeleton with gussets wherever they saw fit, while also reshaping its subframe to their liking. The original swingarm has been deleted altogether, making room for a boxy aluminum substitute that’s 15 millimeters (0.6 inches) longer than stock.
It’s considerably wider, too, allowing for a fat rear wheel to join the party later on. Bull Dock took care of the suspension before addressing the footgear, and this is where the Nitron paraphernalia came into play. At the front, you will now find 43 mm (1.7-inch) telescopic forks with high-grade internals, while the rear end carries a pair of NTR R3 shock absorbers. These bad boys feature progressive springs and piggyback reservoirs.
Photo: Bull Dock via Return of the Cafe Racers
Down in the unsprung sector, the motorcycle flaunts 17-inch Lavorante hoops made of carbon fiber, and their rims are shod in sticky Bridgestone rubber. Abundant stopping power was on the grocery list, as well, so Bull Dock installed top-shelf Brembo calipers and rotors all-round. The front setup is particularly enticing, with twin floating discs pinched by radial calipers.
Those swanky braking upgrades would be vital, mind you, because the Japanese specialists were looking to extract a considerable dose of extra grunt from the Z1-R's inline-four mill. They bored it out to 1,203cc, while replacing the pistons and cams with high-performance aftermarket parts. New titanium valves and springs were also added, along with a fresh set of Mikuni TMR carburetors breathing through velocity stacks.
In addition, we see a stunning four-into-one exhaust system made of titanium, and it works in unison with the aforementioned mods to unlock a total of 150 hp. This force makes its way to the rear wheel via a six-speed gearbox equipped with a quickshifter, which is a significant improvement over the standard five-speed.
Other drivetrain-related enhancements came in the forms of replacement sprockets, a modern clutch, and all-new sprockets. Bull Dock really went to town here, turning the vintage Kawasaki into an absolute animal! Their transformation was no less intriguing from a visual standpoint, but the bike’s custom outfit doesn’t stray too far from the original.
Photo: Bull Dock via Return of the Cafe Racers
Basing their design on the Z1-R's stock fuel tank, the guys fashioned a custom aluminum alternative from scratch. Right behind it lies a fiber-reinforced polymer tail that merges with the seat pan and side covers to seamlessly form a single unit. There’s a tailor-made solo seat placed up top, along with snazzy carbon fiber add-ons fore and aft.
CFRP was once again the material of choice for crafting the front and rear fenders, but it shows up in the cockpit area, too. It does so as a bespoke instrument cluster panel and sporty mirror housings fitted straight onto the handlebars. As for the instrumentation itself, it consists of a fuel gauge, four warning lights, and an ST200 Clubman tachometer from Stack’s inventory.
You’ll encounter a billet top clamp a bit further back, and there’s also an aftermarket steering damper to aid with stability. Clip-on handlebars finish things off in the cockpit, sporting Galespeed brake and clutch master cylinders, as well as the repurposed switchgear of a newer Kawi. All this paraphernalia is fronted by a custom-built fairing, which was styled after the factory component just like the gas tank.
In terms of paintwork, the cyan-finished springs worn by the Nitron shocks set the tone. The ravishing hue got carried over to the bodywork, and it was subsequently topped with white highlights. Pinches of cyan can also be seen on the front brake rotor flanges and Brembo caliper logos, while a mesmerizing purple tint is present on the upper forks. Joined by the titanium exhaust, some red accents, and a teeny bit of gold, the color palette chosen by Bull Dock is pure bliss.
A bit of an artist himself, Silvian sees two- and four-wheeled machines as a form of art, especially restomods and custom rides. Oh, and if you come across a cafe racer article on our website, it’s most likely his doing. Full profile
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