RIGINALLY I BOUGHTthe ZRX because I wanted an unusual track bike. Everyone rides sportbikes, I wanted something a little bit more challenging. Plus, I’m pretty slow and it’s nice to have a shitty bike to blame the lousy lap times on.” As you can see from the pictures,despite his initial intentions, Magnus Wallner’s Kawasaki ZRX1100 is anything but shitty. In the last few years he has converted a 225kg naked bike with suspect handling and an unimpressive 106bhp into a 190kg road-legal racer that boasts 160bhp and a chassis that can match most sportsbikes.
“I bought the bike in 2011 as a standard 1998 ZRX1100 ‘Eddie Rep’ in the less popular blue/silver paint scheme,” remembers Magnus. “I like the classic look of the ZRX and the fact that it’s a nod towards the KZ1000 Lawson raced in AMA Superbikes. The tubular steel cradle frame housing the big inline four is cool and I love the tubular alloy swingarm. But, while in 1998 it was pretty sporty, by 2011 it really wasn’t.”
Kawasaki ZRX1100 Owner's Manual PDF
Despite fully-adjustable suspension and six-piston calipers, time had certainly taken its toll on the ZRX.While it might have been being the sportiest of its class,that’s not saying a great deal when the competition is the lardy Suzuki GSX1400 or wobbly Yamaha XJR1300. The ZRX certainly carries a lot of excess fat;at 225kg dry it’s not exactly a lightweight. “The original plan was to fit a race exhaust, carb kit and remove some weight, but then it all got a bit out of control,” admits Magnus. “I’m a huge fan of the DOBAR racing scene in Japan, which is a series especially set up for retro naked bikes, and so I looked at them for inspiration. I got involved in the ZRX online community and they steered me towards a guy who lives in Japan (www.moriwaki-man.com) and who specialises in sourcing rare parts you normally can’t locate outside Japan. At that point I kind of had no choice but to go all in.”
And when he says ‘all in’, Magnus really does mean it. He stripped the bike back and started with the chassis. The weedy ZRX forks were replaced withsome custom-built Öhlins FGRT units that are a combination of ZX-10R uppers for length and Yamaha YZF-R1 lowers to accommodate the uprated brakes.Handily for Magnus, Öhlins are a Swedish company,and he lives in Sweden. So, after a bit of discussion about what he was planning, the firm advised him to upgrade the shocks to CB1300 Öhlins units ratherthan ZRX-specific ones. Despite lacking the hydraulic preload adjuster, the Honda fitment shocks have better valving, according to Öhlins. And then it was off to another Swedish firm to make everything fit and the bike stop properly.
Kawasaki ZRX1100 Service Manual
ISR have been building frames and brake calipers in Tumba, Sweden, since 1968 and have even supplied calipers to Kenny Roberts’ 1991 500GP team. Their massive six-piston calipers slotted into the Öhlins R1 fork lowers and while he was there, Magnus got ISR to build him some bespoke triple clamps to hold the forks in the frame with a 5mm increase in offset.
“I didn’t want to hack around the frame itself,” said Magnus. “So it is standard and has the same geometry as before. However, the combination of the new yokes and race tyres has decreased the trail from the previously conservative 107mm to a more extreme 92mm. The tubular steel design isn’t as strong as a modern aluminium beam frame, but I have added some Tsukigi Racing billet aluminium frame braces.When Tsukigi raced the ZXR in the early 2000s around Suzuka they were only two seconds slower than the fastest WSB bike using a stock frame. What’s good enough for them is good enough for me.”
Kawasaki ZRX1100
Quick steering, however, isn’t only about geometry it is also about gyroscopic forces and the stock ZRX wheels created enough force to influence tides. They had to go, and Magnus located a set that were sympathetic with the retro theme of the whole bike.
“I know the classic cast magnesium Marvic Penta wheels aren’t the best in terms of weight loss or strength,” he admits. “But I’ve had a thing for the Penta since the 1990s and they are certainly way better than the stock Kawasaki wheels!”
Despite the shorter trail, a few test rides convinced Magnus the ZRX didn’t need a steering damper. But this has now changed. Over the long Swedish winter,when the roads were covered in snow, the Kawasaki’s engine has been through a thorough transformation.
“Kawasaki claim the stock engine makes 106bhp,which jumps to 120-125bhp with a free-flowing exhaust and proper jetting. This isn’t on a par with the rest of the bike, and so something needed to be done.” Turning to experienced Swedish tuner Motospeed,Magnus has had the engine’s capacity increased from 1052cc to 1109cc and fitted with JE forged pistons and Carillo rods. The stock crank was sent to APE in
ENGINE
Up from 1052cc to 1109cc. Fitted with JE forged pistons, Yoshi cams,ZZR double valve springs, Carillo rods, APE lightened crank and ELS slipper clutch. Six-speed box is from a ZZR600 and the ignition system from a ZZR1100. Fed by Keihin FCR39 flatslides, makes around 160bhp and cooled by a ZX-7R rad