PROJECT ZX990 TURBO
1990s WSB icon with 2019 WSB power, courtesy of a turbo. PS’S ambitious/daft new project starts now. Target 250bhp
We take a manky ZX-7R and a tired GSX-R1000 to create a savage blown hybrid
new project has been near the top of our priority list: PB recently finished its 2008 Fireblade project with great success, and PS has taken a bit of a breather since its last big build. Time to get busy, and also make use of the combined knowledge now at hand. Modern expertise with retro appeal.
So we scoured the small ads, browsed the web and drew inspiration from every source you’d expect, before the plan began to form. A few year back, Scandinavian custom shop Wrench Monkees slapped a ZX-7R fairing on a new Kawasaki H2 and called it a ‘build’. It was bobbins: the fairing jarred with the size and layout of the modern chassis. It looked what it was: tacked on. Same goes for a Z900 naked recently dressed up like a ZXR750 H1 – a little better finished, but an unsuccessful marriage of retro appeal and modern parts. But not a bad concept…
The ZX-7R is a PS favourite: a chassis with good fundamentals and timelessly cool styling: you can’t go wrong with a 7R in these respects. But they were always heavy, and the motor deserved some development, but never got it. They’re also cheaply built, and only the most cherished of them last well.
Ours is not cherished. It is a minger. It cost us £1400, as values are reasonably strong and anything around or below a grand was either incomplete, damaged or hooky. Or a combination of all three. This seemed the threshold for a complete starting point.
It’s a 1997 parallel import, wearing all of its displayed 49,000km (30,000 miles) and probably more besides. It has been dropped: the fairing sides resprayed well, the top badly touched-up. The brakes are binding on cheap wave discs fitted with iridium-effect bolts. Poorly-touched-up paint barely hides the corrosion that blights the wheel rims and exhaust. The radiator has chunks falling off, the shock is goosed, and the choke doesn’t work. It might look OK in pics, but the more we looked the worse it got. But it’s all there, and straight. Something to work from.
To give it 21st century appeal, it needs better running gear and more power. Lots more. Over 100% more, in fact, we’re going to target Kawasaki’s supercharged effort. No sense in even considering the original engine. So it’s coming
out. The running gear needs to do likewise. At this point, the 2003 Suzuki GSX-R1000 in the pictures may begin to make a little sense…
A number of ZX-10R powered ZX-7RS exist: a neat conversion on the face of it, giving the over-engineered ZX-7R chassis the sort of power it was meant to handle as a WSB racer. But the engine itself is an awkward lump with completely different engine mounts. There are off the shelfkits available, but they’re a bit Heath Robinson. The best conversions involve some compromise.
A less popular conversion, for reasons of brand allegiance we assume, is an early GSX-R1000 engine. It requires less cutting, and the engine mounts are in very similar places, so the load on the chassis is closer to what Kawasaki intended. It’s also lighter than stock, with 150bhp or so as standard. And it’s a better start point for the icing on our green and blue Battenberg: the GSX-R lump is a gleeful recipient of a turbo…
Forced induction was the detail that sold us on this course of madness – we can expect anything between 200-250bhp even with modest boost. That at least puts it on equal footing with the H2 – possibly better off. It’ll tick the ‘modern performance’ box, while keeping some of the best lines ever created by a Japanese manufacturer.
We’ve picked up a complete GSX-R1000 K3: tidier and lower miles than the ZX-7R (19,000 miles), and a top buy at £2650. It also shows signs of a minor drop: bent gear lever, grazed crash bung, and a coat of white on the seat unit where it should be blue: probably a partial repaint to cover light damage.
We chose this route as buying a motor, throttle
“WE CAN EXPECT ANYTHING BETWEEN 200-250BHP EVEN WITH MODEST BOOST. THAT PUTS IT ON EQUAL FOOTING WITH THE H2 – POSSIBLY BETTER”
Clockwise from top: we’ll be having that engine thank you. Nasty, nasty hugger. ZX-7R mingin’ beneath the plastics. And pretty grotty all over if truth be told. Good ones are rare these days
bodies, loom and electrical parts would cost almost the same. It’s less hassle and less cost in the long run, especially when we sell the leftovers from both to replenish the coffers (and clear lockup space). We’re not going to be missing anything, as can be the way when you start with incomplete bikes or parts.. It also comes with a good set of modern forks and brakes – we may well use those, too.
A preliminary measure-up confirms what the internet told us: the two motors are roughly the same size, the engine mounts not far apart. The fabrication job there shouldn’t be too difficult, or involve compromising the main chassis in the way the ZX-10R conversions do – drilling into castings, cutting lumps from frame spars and the like. It would appear that our work involves only the outlying bracketry.
Packaging coolers and the turbo itself shouldn’t be too problematic within the generous confines of the Kawasaki fairing (when we’ve picked a turbo expert to help us with that end of things. We may use the Suzuki forks, and a ZX-10R swingarm might have to go in to add a little wheelbase, just for grip and wheelie control reasons. The H2 has a suite of rider aids to stop things getting nasty: not an option open to us, so we’ll need to create as much mechanical grip and chassis control as we can…
We’ll be gutting the pair of them next month and starting the job of marrying the best of the ZX-7R with more modern performance. Though we’ll need to do some cleaning first: firing the GSX-R up to move it about, we were suddenly enveloped in a cloud of smoke as lube spewed from the oil filter O-ring over the headers. Engine off, spill kit out. The filter wasn’t even finger tight. Apparently the recent services have been carried out by ‘a mate who used to work in a Suzuki dealer’. If that’s the truth, I think I know why he no longer works for them… We’ll be checking the motor’s apparent integrity before it gets large amounts of pressurised air-fuel stuffed through it then.
Still, that’s nothing: then there’ll be a fair amount of fabrication work, plus adapting the Suzuki electrical and coolant systems to fit the Kawasaki chassis, then sourcing and fitting better running gear, a turbo, set-up, repainting the whole lot, getting it to handle…
We offer up the GSX-R1000 engine and see just how we’re going to make it sit tight and right
Two donor bikes and three organ donors
Tape measure one of the few tools they can wield with competence
Cursory measurements suggest GSX-R thou lump will breeze in
If you’re after some nice GSX-R bits, we can help
Suzuki shat its oil when filter spun off on start-up. Wonderful