Cycle News - Archive Issues - 1990's

"I can honestly say that the '92 customer race kit effectively reproduces the performance of our bike at the end of last season," says Moving Kawasaki boss Peter Doyle. "Kawasaki did a helluva lot of good work over the winter on the factory race bikes, but the customer got a lot of the benefits of that up front, too." Customers like Terry Rymer (before financial difficulties forced him to take a rest from World Superbike) or Pierluigi Bontempi would certainly agree - but it's been the performance of the works-backed bikes that have really impressed. Though obviously a lot of work has gone into the engine, perhaps it's the chassis improvements which have had most effect, with completely redesigned rear suspension offering a higher rear ride height,' more suspension travel, increased frontal weight bias and. quicker steering. The chassis has been comprehensively strengthened inside the spars, as well as the swingarm, which together with new Ohlins forks and rear shock has' helped to make the bike more nimble in turns, but especially to cure their biggest problem. last season; a lack of traction out of turns. Now that Michelin tire . development is back on pace, that's also been a factor, but now the bike is hooking up properly at the back end, all three teams have had some problems with the new front forks chatter_ ing, especially at Donington, though to be fair, this was a common problem with other bikes. Weight is a problem, as in '91: the bikes have to be carefully loaded up with legal ballast like generators and the like to meet the 363 lb. weight limit - Doyle says the ZXR could easily scale 341 Ib_ with no expense whatsoever, and 330 lb. is within easy reach with a little budget and time. The ZXR750 motor is largely unchanged for this season, with 145 bhp available at the gearbox, at 13,800 rpm. Phillis has experimented again with the lighter crank he tried once or twice last season, but the throttle response is much snatchier and they needed to set it with a 3000 rpm idle to avoid unhooking the back end when Aaron Slight went out to use it for qualifying at Albacete, with all its slow turns - a choice which also dictates a completely different set of carburation settings - needles as well as jets - so responsive is the ZXR engine to any small changes, whether of internal specification or external ambient weather conditions. Perhaps the VEMS'system, Kawasaki's variableexhaust answer to Yamaha's EXUP system, might come in useful here, Kawasaki's ZXR powerplant has changed very little since last season. Rob Phillis and Aaron Slight have experimented with lighter crankshafts during the season. except it's dropped by the wayside as development has ceased for the time being. Instead, Kawasaki has an allnew exhaust system this year, with much larger header pipes and a bigger '92 kit collector. Main engine development has been on the midrange power, which now .comes in stronger and faster than before, giving a very acceptable 750013,800 rpm power band with the sort of midrange than now enables the Green Meanies to match the Ducatis' pickup out of turns - the Italian bikes' main forte, thanks to their lighter weight and V-twin torque. Kawasaki is there - but they also have a definite top speed advantage, trapping 180 mph at Hockenheim according to their telemetry system. That's quick, and as Scott Russell's thrilling defeat of Doug Polen's World Championship titlewinning Ducati at Daytona proved, the Kawasaki has an definite edge on ultimate top end - that's how the Georgian was able to pull out and pass the Texan 200 yards from the line to win. Yet, as the Hockenheim result showed, Ducati still has an edge in terms of all-round speed performance, measured in terms of how fast you get to your maximum speed, as much as the speed itself. Conventional wisdom questioned Rob Muzzy being able to reproduce his Daytona-winning performance on 38mm stock World Superbike-legal carbs once he'd taken off the 41mm flatslides Russell used in Florida, but the American tuner experimented with different inlet lengths on the dyno after Daytona, and was able to come up with comparable horsepower figures on the stock carbs. Working very much on a separate development track than the factory/ Moving Kawasaki teams, Muzzy (Above) Mwzy's Kawasaki uses 330mm front discs with four or six-caliper pistons. (Below) Mwzy has tried fuelinjection, but the ZXR still uses carbs. Muzzy bikes also stand out: the Performance Machine spun aluminium wheels, which each weigh the same overall as a comparable Marchesini, but are no less than 30% lighter on the rim, leading to a huge reduction in the rotating mass. Muzzy's used them for three years with no problems: They're made as one solid component, with the spokes milled out later though some people don't bother if looks are more important than weight! The same company makes the 330mm front discs fitted to Russell's bike, with aluminium billet four-piston calipers: a six-piston version is also available. Interestingly, Muzzy is one of the few people outside a Japanese factory to have experimented with electronic fuel injection on a four-cylinder Japanese bike, when he ran a ZXR750 in Formula USA events in 1990. His conclusions are interesting, and all the more apposite given Honda's rumored introduction of EFI next year on their new V-4 Superbike. "We found no real performance increase at all," he says, "only that once it was correctly programmed, we could always be sure of having the optimum setup for any prevailing weather conditions, especially if.these changed during the race. But I don't think EFI is either desirable or necessary.for this kind of motorcycle, firstly because of cost, and secondly because carburetors are so refined and effective nowadays - there's no need. Something like a Ducati with those big cylinders - that's another story. But we don't need EFI on the Kawasaki, and I'll be surprised if we see it on this bike in the near future - and don't forget Kawasaki already marketed a fuel injected motorcycle 10 years ago!" The only persistent problem Kawa. saki runners have encountered this season - apart from red bikes with the word Ducati written on them! has been a difficulty selecting bottom gear, presumably due to either a design Muzzy's ZXR uses Pedonnance Machine spun-aluminum wheels, giving Scott Russell's bike a huge reduction in rotating mass because they are 30% lighter on the rim. ~elieves his engines have "a 5 or 6 horsepower advantage overall, plus my I motors make real power at 14,000 rpm, but their's peak at 13,000, plus we have great engine speed pick-up from 9500 to 1l,500 rpm." Muzzy also runs a higher compression than the other Kawasakis, using specially blended - but presumably completely legal....:. Powermist fuel he brings over from the States. He has three different versions of his own exhaust systems, which help to give the power characteristic Muzzy engines are notable for - more power from the midrange up than comparable motors prepared elsewhere. Then put a brave, fast rider like Scott Russell aboard, and - stand back! Two U.S.-sourced aspects of the or manufacturing fault. Both factory and privateer riders have suffered from this alike, leading the Moving team to gear their bikes to run only the top five gears at Donington, for example. But once this little difficulty is rectified, as it surely will be, the green bikes will surely confirm their position as the only serious challenge in numbers to Ducati's dominance. If they didn't have that 55 lb. handicap, World Superbike would likely be painted green all over in 1992. CN Next week, in part two of our Superbike tech review, we'll take a look at the bikes fielded by Honda; Suzuki and Yamaha in the WorId Championship Superbike Series. 19

• Cover