The Japanese street racing scene has largely been known for the 300km/h Midnight Club and their flashy two-wheeled rivals, the Bosozoku, who always preferred looks over speed. But if you get to talking to the older motorcycle tuners in the Land of the Rising Sun, their inspiration comes from a much lesser-known group that preceded them all, the Kaminari-zoku. The ‘Thunder Tribe’, like their British and American biker brethren, were post-war outcasts who loved riding their motorcycles as fast as they possibly could on public roads. The times may have changed, but Iwaki city’s MG-Nest is heavily influenced by that gritty brat era and their penchant for huge horsepower. This Kawasaki KZ1000 is the personal machine of head honcho, Takanori Shiine, and it’s a perfect mix of ferocious speed and a punk rock personality.
The team at MG-Nest are 110% dedicated to building ultra fast Z bikes, and they’re not just quick on the street. The same engine package as used in this bike has been fitted up to motorcycles competing at the Taste of Tsukuba event at the famous circuit, by clients racing in the JD-Ster drag racing series around the country, land speed attempts and just about any other way you could think of if you have a serious need for speed. So, how does Shiine-san use his bike? “I’ll use it for anything,” he smiles. And he means it, as you’ll come to discover, this motorcycle with its brat looks and almost run-down aesthetic, is capable of mixing it up with just about anyone racing in an air-cooled class.
Even more amazing, is that despite laying down over 150bhp to the rear wheel, this engine package has been in the bike for over 5 years, which gives you an idea of just what good tuners these guys are. Shiine-san does say that the bike is down a couple of horsepower from its early days, but that a simple valve job is all he needs to do to have the powerplant making peak power again. This engine, like the one the team took to El Mirage in the USA, starts with a crack tested lower case and is then fitted with a fully balanced crank from TIS, and a 5-speed gearset from Three Wave which is designed to be able to not only handle the horsepower, but brutal flat shifting as well.
The upper case is from the guys at APE, who are the MPH kings in Z series drag racing, being the first to crack 200 and go on to speeds over 240mph. Inside the big block, a set of custom 78mm JE forged pistons drop in and help to punch the capacity out to 1260cc, while 2mm skimmed from the head brings the compression up to the point that you need to run premium gas. Having sorted the bottom end, up top the head is heavily ported, and the big WEB cams are designed to maximise the ramp rate. Making the most of that extra airflow, the guys prefer to use the RS variants of the popular 36mm Mikuni carbs, while the exhaust is all built in-house, including the big megaphone muffler.
But before the power package can be tuned on the company’s chassis dyno, you have to get the horses to the rear wheels, and it’s here that Shiine-san is far more serious than most street bike based riders. The clutch is a full MTC two-stage lock-up clutch, which can be tuned using the internal weights on the pressure plates for either blisteringly fast 60-foot times at the drag strip, or backed off to be rideable on the street. There is an offset sprocket and 520 chain conversion, and given how ferociously the engine unleashes its power, the D&G Chassis cover with its extra bearing support is a must!
The chassis, of course, has been braced in all of the right places, but purists will be happy to know that this machine rolls on 18-inch wheels, made by another old school shop JB-Power, supplying their magnesium MagTan JB-1s for each end. There’s even more classic cool with the Moriwaki 36mm front forks, with a GPZ steering stem to get the offset to the desired number. At the back end of the bike is a seriously clever piece of kit, with the BS oversized alloy swingarm featuring an internal oil catch can, a very smart use of space. The rear shocks are fully adjustable Ohlins items, and sizeable Brembo calipers matched to Sunstar discs take care of the braking.
When it comes to looks, Shiine-san will happily build a beautiful bike for his customers, but given how hard he beats on his, the practical punk effect is his chosen aesthetic. The fuel tank has been swapped from the round Z unit to the later model KZ1000 item with its squared-off lines. It was in relatively good condition when he got it, and after sealing the inside, the hand lettering and effects were laid down by Shakin’ Speed Graphics. The factory seat has simply been recovered to deal with the sun damaged original, and under the factory tail is a vintage Bates light. The front end gets a similar theme, and the chrome fender sits proudly in place.
A lot of effort has gone into getting the riding position spot on, you don’t want to be uncomfortable at the sort of speeds this machine is capable of. Custom risers hold a set of Nest’s own laid back bars, with the footpegs a combination of Moriwaki’s Z rear base plates and Ito Z controls, using a custom linkage on the clutch side to clear the big cover.
A set of indicators keeps the law happy, but sandwiched between the front items, the massive 9-inch 13-stage oil cooler shows you just how serious Shiine-san takes thermal management. MG-Nest might not attempt to compete with the likes of Sanctuary and Bulldock in the looks department, but whether on the street, staging lanes of the strip or racing around Tsukuba circuit, Takanori Shiine proves following in the footsteps of the old school is still a blistering way to build a bike.
[ MG-Nest ]