Cycle News - Archive Issues - 1990's

RACER TEST Kawasaki ZX-7RR (Left) Variablelength In18kes were experimented with, but the team stuck with the s18ndard setup In the end. Both 39 and 41mm Kelhln FeR fiat-slides are homologated. (Right) InvertBd 46mm Ohllns forks grace the front of the Muzzy bike. tBelow) Gobert's ZX-7RR Is fitted with a perfectly set up KLS speed shifter. tire neared 40 laps in age, it felt more and more like ricling on ball bearings, especially on a track like this with a new, very a tringent surface. Time for a change - and some work on the suspension. Becau e even with an increasingly chronic lack of grip, the KawasalG was pumping up and down when I got hard on the gas out of a turn - usually a sign that the rear shock's too soft for my, er, extra pounds compared to the superstars who race these things for a living. But while Anthony is incredibly muscular and fit, he's also quite chunky, and our body weights are pretty similar - so think again. 1'd already experienced his distinctive dirtbike-derived ricling position last year when I rode a green Gobert go-getter for the first time (though Crafar uses a similar layout and sits even more upright, because he's taller), and it still feels just as strange as the first time. Wide-spread handlebars and a far forward, upright stance, delivered courtesy of a two-inch thick rubber pad on the back of the seat, quite stiff front suspension and what felt like a soft rear all combine to produce a bike you need time to feel comfortable on, and even longer to be able to ride hard. I was some seconds slower on the KawasalG than on the Colin Edwards II Yamaha I was riding the same weekend, which felt much more taut and together. Still, that' what test days are for, and since Craggill - deputizing for his injured fellow Aussie - had exactly the same problems as me (and Crafar, who wa going much faster, suffering the ame only· worse). Chief wrench Larry Kano and Anthony's Spanish mechanic Pedro Parajua tore into the bike and rejigged the setup. The chief culprit was a shock later found to have a defective part inside, but a series of gradual setup improvements delivered a bike that wobbled less alarmingly hard on the gas, and with a fresh rear tire, started to put the power down well. Overnight, they built me a new shock - and next morning I had an object reminder in how crucial suspension setup is if you want to go fast - okay, faster in my case on the Muzzy ZX-7. "We checked the wheel rate on the telemetry, and determined that the new track surface gave so much grip, the tire was actually deforming," Cornwell explained. "Because of that, it transferred everything into the shock - there was no su pension left in the tire carcass. "Basically, all we did then was to lower the wheel rate by goi ng to a softer spring with a bunch more preload - more than one kilo softer on the spring, which is a lot. This kept the ride height the same, allowed the shock to use a longer stroke and kept the integrity of the tire shape. Shows how cri tica I telemetry is in setup everything pointed to the rear being too soft, but in fact it was way too hard." Corner speed is really only a factor twice per lap at Albacete, the most important being the last turn onto the main straight past the pits. After suffering wheelspin and wobbles aplenty on day one, I now had the KawasalG carrying lots of speed into the turn, riding the bump in the middle without getting out of shape, then hooking up well for a good drive over the line - the fork settings on the 46mm Ohlins felt really good, with lots of feel from the grippy front Dunlop. . But even so, I found myself getting zapped in a straight line three-quarters of the way down the straight by both Yamahas (Edwards and Wataru Yoshikawa), as well as a deluge of Ducatis. Okay, T might not be go-getting on the gas quite as hard as the Go-Show, but by the time 1'm straightened up and flying right, I can twi t the wrist wide open as well as the next guy. What gives? Only the problem Gobert and Crafar had to live with all season, namely a surprising lack of top speed with the new short-stroke engine. Frankly, this was a disappointment - it hasn't got the appetite for revs of the previous ZXR750 speed king, which built power strongly and ran freely all the way to 14,500 rpm and beyond - yet still pulled cleanly off the bottom from 8,000 rpm upward. With all Albacete's slow turns and short squirts, I'd have much preferred to be riding the older bike, because even with the same, smaller-size 39mm carbs fitted for the tight Spanish track, this new motor had nothing much on tap below 10,500 rpm, beyond the kind of poodle-power you use tootling around warming up rider and rubber. But there's serious midrange punch on tap once you hit the power threshold, though it comes in smoothly enough not to unhook the back wheel if you gas it up hard out of a slow hairpin and wait for that magic; moment to·arrive. Then it starts to build revs fast - but by 14,000 rpm, it's all done. You can feel the engine peak at just below that mark, but though it doesn't dip the power curve before the rev limiter starts fluttering the ignition at 14,500 revs, it also doesn't seem to want to keep on pulling so hard up high. Not an easy bike to ride hard - you have to really work at getting the best out of the engine. Being left with a relatively narrow 3,500-rpm effective powerband encourages you to use the KawasalG's gearbox like a two-stroke GP bike and highlights the importance of tightening up the gear ratios to keep the engine on the boil. Fortunately, the KLS speed-shifter fitted to the Muzzy bike is perfectly set up, with exactly the optimum duration of cutout for each ratio determined by the telemetry, and dialed into the system to provide clean, crisp upward changes with just the right amount bf sensitivity. It made using the gearbox a pleasure, and was an object lesson to the works Ducati teams to aim at in their setup of the same German kit on their bikes. But even though the ZX-7 was geared to use only the bottom five ratios at Albacete, I found myseli changing KAWASAKI ZX·7RR 5pecificalion Uquid-cooled OOHC in-line four-cylinder four-stroke with four valves per cylinder and offset gear camshaft drive 73 x 44.7mm Engine Bore x DIspI.c _....•. _ 749cc _.Over 155 bhp at 13.500 rpm

• Cover