In Japan, a distinctive trend emerged: the resto-modification of motorcycles from the 1970s and 1980s, which were previously inaccessible due to the post-Nanahan trade agreement restrictions on domestic bike imports. Following the introduction of the Nanohan regulations in Japan, motorcycle manufacturers were limited to producing bikes with engines no larger than 750cc and generating no more than 100 horsepower. Many legendary motorcycles, such as the Kawasaki Z1, Suzuki GSX1100S Katana, and Honda CB1100R – all originally built in Japan – were largely exported to various global markets. In Japan, renowned restoration specialists like Masahiro Wakui’s esteemed workshop, Bull Dock, meticulously preserve and upgrade classic vehicles into national treasures.
For over two decades, Masahiro has been passionately reviving the heritage of iconic Japanese motorcycles by importing them back to their country of origin. In America, where second-hand options abound at affordable prices, he stocks up on containers. The vessels are subsequently stored at Bull Dock Headquarters until a suitable buyer returns to make a purchase.
Bull Dog’s specialty lies in traditional Kawasaki fashion designs reminiscent of iconic models such as the Z1, Z1000, and Z1R. While they may venture into other iconic Japanese classics, it’s undeniable that their expertise lies in timeless Kawasaki masterpieces. The Bull Dock company brands its meticulously crafted resto-mod creations as GT-M, a cleverly coined acronym that proudly proclaims its commitment to authenticity and precision engineering through the phrase “Real Tuning Machine”. Since these bikes are designed for riding on the road, their construction raises questions about whether they truly live up to their “race-bred” label? These products include the epitome of modern efficiency, seamlessly integrating with elements that are both rapid and incredibly dependable. Masaaki’s skilled team of craftsmen produces approximately 20 high-performance GT-M models annually, with each employee dedicated to building an entire bicycle from start to finish.
Meet the second Kawasaki Z1-R GT-M to have the honour of featuring on our platform.
The final reveal was Bull Dock’s stunning 1230R Nitron version, dubbed Z1-R, born from a collaborative effort with the renowned suspension manufacturer. While the two bicycles share numerous visual parallels, this vibrant orange Z1-R stands out for its unique character and distinctiveness.
The Kawasaki Z1-R is equipped with a revised Sort 1 z1000 engine, boasting a bespoke Z1000J cylinder head installation. This modification enables Bull Dock to execute a series of internal enhancements aimed at boosting efficiency while maintaining reliability. Among the modifications implemented were larger valves, optimized consumption and exhaust porting, 76mm Cosworth-style high-efficiency pistons, and refined combustion chamber designs. The bike also features an efficiency-enhancing ST-L1 cam developed by renowned racing tuners Yoshimura, in addition to a high-performance Bull Dock hydraulic clutch seamlessly integrated with the Kawasaki’s latest 6-speed transmission. You’ll also notice McCoy branding on the engine components, specifically Bull Dock’s own proprietary line of aftermarket parts. The comprehensive titanium exhaust system features a Win McCoy Neo configuration, while fuel delivery is ensured through four precision-crafted Yoshimura Keihin FCR-MJN carburetors.
The outcomes of these modifications have significantly enhanced the performance capabilities of the engine, expanding its displacement from 1015cc to 1197cc. According to Bull Dock’s stored energy data, it is likely that the bike’s horsepower exceeded its original 90hp figure, which was recorded at the Kawasaki factory in 1978.
With a focus on crucial energy enhancements, Bull Dock devotes meticulous attention to the operation and maintenance of its GT-M machines. As a standard practice, the company thoroughly re-designs each bicycle’s frame, incorporating reinforced gussets to optimize energy transfer and overall stiffness. They meticulously adjust the engine’s mounting to precision-calibrate each bike’s centre of gravity for optimal performance. Upon this construct, elevating the engine by 10 millimeters and extending the rear shock absorbers. Efficiency wheels also offer a significant advantage by reducing unsprung mass, which consistently yields substantial handling improvements. Here they arrive in the guise of Marquezini M10RS Corse 10-spoke magnesium rims, their lightweight construction boasting an astonishing 40 percent reduction in weight compared to standard wheels. The Bridgestone Racing Street R10 tyre completes the comprehensive offering.
Leaving no stone unturned, the stopping energy and suspension systems on this Z are completely revamped for a smoother ride and enhanced control. The braking system employs Brembo calipers paired with radial master cylinders, coupled with Sunstar rotors; two at the front, and a single unit at the rear. Bull Dock sought another opinion from Nitron regarding its suspension, seemingly uncertain about a decision.
Nitron’s distinctive black finish replaces their signature turquoise hue, revealing a pair of R-series piggyback shocks that support a lightweight aluminum McCoy swingarm. At the front of the bike, a set of 43mm Nitron-tuned forks rest in Bull Dock’s custom variable offset triple clamp setup.
Bull Dock has crafted a comprehensive range of FRP and carbon fiber bodyworks tailored to specific bike models, complemented by a suite of performance-enhancing components. The motorcycle is adorned with a distinctive McCoy Z1-R type entrance cowl, accompanied by sleek facet covers, a streamlined single-seat rear cowl, and a sporty stomach pan design inspired by high-performance racing. With its sleek design, the rear cowl proudly showcases a carbon fibre panel cleverly disguised as a pillion seat, preserving the distinctive appearance of this one-of-a-kind bike. The exact design features a two-piece McCoy setup, accommodating a single occupant in ample space. To preclude highway grime from disfiguring this elegant vehicle, the rear wheel is protected by a McCoy carbon fiber cover.
Every aspect of the Bull Dock GT-M has been meticulously engineered to maximize performance and efficiency. Although these high-end features come with a premium price tag, it’s undeniable that these bicycles offer exceptional value for money. This bicycle appears to be meticulously crafted with every detail carefully considered, much like a prized possession.
Pictures by Customized Individuals & Bike Bros.
