Custom by BITO R&D | Kawasaki Z900RS Custom Project: Beyond Z

The Z a world-class tuner builds for himself

Renowned Kawasaki Z tuning shop BITO R&D is located deep in the sparsely populated mountain woodlands of Toyooka, Hyogo. The middle of the quiet woods is the last place you would expect to find a large factory, so when it suddenly appears it’s like stumbling upon the secret base out of a movie scene.

“I cut through the mountain to create this level ground. Operating an excavator is so much fun,” chuckles owner Jo Bito. “We’re still expanding. In the near future, I’d like to build a staff cafeteria and a park-like factory. After all, isn’t it extremely important for human beings to create a comfortable atmosphere? With that, I think we will really be able to produce pieces that are used all over the world.” In 1976, he joined Yoshimura R&D, right when Pops Yoshimura was making his comeback in the AMA Superbike Championship. He soon distinguished himself as a mechanic, and was engaged in the development of Z1-base production racers. After that he got calls from Suzuki and Honda, and moved up to World Grand Prix to work as a mechanic in the pinnacle series of motorcycle road racing. In 1983, he returned to his hometown of Toyooka, where he started this company. He is a big deal in the industry – ask anyone and they’ll have heard of him – and although he will speak frankly about his achievements, his demeanour is modest and his personality charming.
BITO R&D receives orders from everywhere in the world. From carburettors and pistons, to mufflers and wheels, the requests are many and varied. These include orders from factory teams battling in MotoGP. Incidentally, JB-POWER MAGTAN wheels – a product synonymous with BITO R&D – were used by both Kawasaki and Suzuki’s MotoGP teams. Even at the highest level of competition, the world-class level quality of this engineering group is recognised.

“The clients that come to us are generally pretty eccentric. They are all very particular, so they don’t change, and don’t get swept up in the times – which is how a small company like us is able to keep going. Our business caters to the minority.” Bito-san explains that he has gotten this far by making things he thinks will be fun. His clients are people just like he is. Fulfilling their wishes is his job as a craftsman. He wants to please his customers, for them to be happy. And if he can make money doing that, nothing could be better. To avoid losing himself in today’s rapidly changing world, he believes it is important to be able to return to your beginnings. With that in mind, since he started this company he has lived in the countryside, surrounded by nature.
Like the Z1, an accommodating character that can handle anything

As an acknowledged Z authority, what was his first impression of the new Z900RS? “It’s a beautiful bike that conveys its Kawasaki-ness everywhere. Even though it’s liquid-cooled, the engine has fins carved into it; the tank has a rugged presence; the suspension and brakes are good quality, and the bike handles well. Late-model In-Line Four engines tend to spin up too smoothly, so they lack character. But with the Z900RS, the feel of the torque building from the low-mid range is good. You can really sense the heritage of the Z1,” Bito-san enthuses. Of course, there will always be customers who feel that in stock form the bike is missing something. “For those people, I think figuring out what we can do for them and then making it a reality is the work we do.” For this project, Bito-san, a master craftsman who knows the original Z1 series inside and out, built his Z900RS custom as if he was his own client.
“The Z900RS handles like a modern motorcycle: it’s light and turns well. However, if it was up to me, I’d prefer handling that was a little more relaxed. So, I changed to 18-inch wheels, and specifically selected thinner tyres,” explains Bito-san, whose goal was to realise a “go where you think” feeling. To be able to ride confidently, feeling that you are in full control – handling that imparts those feelings to the rider offers a deep level of enjoyment.

To achieve this, he fit original 18-inch JB-POWER MAGTAN wheels front and rear. They weight about half as much as the stock wheels, reducing unsprung weight while contributing to light, composed handling. Functionally, the standard brakes perform just fine as is, but when he thought about what he would want to own himself, he opted for machined aluminium calipers with 6 pistons. The standard discs were switched out for cast iron ones that offer superb brake touch and control. When you see the slim calipers with their small-diameter pistons arranged neatly in a row paired with the delicate brake discs, Bito-san’s particular sense of beauty is evident.
The exhaust features a 4-into1 layout suitable for a modern machine. And, of course, it’s made of titanium so it weighs less than half as much as the stock piece. The smooth curves traced by the exhaust headers and their beautifully burnt colouring can only be born from handcrafting. Bito-san shaped the headers himself. The exhaust sound blends light, melodic notes with deep, resounding low tones to create a feel-good sensation. A combination of function and beauty, the exhaust is a rare treasure.

But the bike’s masterpiece is the quick-change mechanism equipped on the rear wheel axle shaft. The system was originally developed to allow quick tyre changes in endurance races, but it greatly simplifies day-to-day maintenance chores. Bito-san’s experience in countless endurance races on the world stage inspired the idea.

“If the concept I had chosen was ‘exceed the Z1’, I think fans would be disappointed that some of the goodness of the original Z1 had been spoilt. Instead I chose to create a machine that is fun to ride regardless of experience or skill level, a bike that can be used in a variety of conditions for many purposes, one that possesses an accommodating character that can handle anything it encounters. Just like the Z1.”
The original “adjustable-offset fork triple-clamp set” was developed to meet that idea. Fork offset can significantly affect handling. Increasing from the 35mm of the standard model to 40mm will result in an even more hands-on, interactive ride feel. Meticulous attention to detail is also evident in the appearance. The engine hangers and fender stays, as well as the headlamp and turn signal stays and other detailed parts are all high-quality machined aluminium pieces. Adding a fully functional rear carrier allows the bike to be cherished as an effective travel tool. Finally, to help bring out the “go where you think” feeling, he revised the essential control points – i.e. the rider triangle formed by the handle, seat and footpegs – to achieve a riding position with a more relaxed posture that allows the rider to more easily feel at one with the bike.
Bito-san shared some additional feelings about Kawasaki. “Even way back then, people used to say their quality was ‘excessive’, but for Kawasaki that was normal. Since their founding, they’ve built ships and airplanes; like the name ‘Heavy Industries’ suggests, they have a different attitude when it comes to build quality. If something fails, a ship would be adrift at sea, and an aircraft would fall out of the sky. Allowing something like that to occur would be unacceptable. I think that the same design philosophy was naturally extended to their bikes. They are the smallest of the Japanese manufacturers, but the enthusiastic support they receive from fans probably stems from that policy.” Bito-san has worked with machines from a number of manufacturers, but Kawasaki’s excessive quality continues to amaze him.

Another element he admires is the beauty of their design. “When functionality is pursued, it becomes beautiful. Or said another way, function without beauty is nothing special,” he explains. By that definition, all of Kawasaki’s legendary machines are cool: from the Mach III to the W1 and Z1, the Z1000 Mk II, Lawson Replica (Z1000R) to the GPz900R Ninja... The teardrop style of the Z1 vs the angular design of the Z1R – even focusing only on the fuel tank design, each is unique in its own way, and leaves a lasting impression. And the new Z900RS? Esthetically it is a worthy successor so receives two thumbs up.

Bito-san’s work creating custom machines that satisfy the desires of Z fans will continue. We look forward to the Z master’s next project.