Cycle News - Archive Issues - 1990's

(Left) Putting the twin silencers on either side of the bike - instead of stacked - improved power delivery. (Above) The conventional swingarm was introduced this year and adopted full time because it gives better feel. (Below) Detail improvements in the gO-degree V-four brought about yet more horsepower. The extra revs really made a difference, too, because Honda's four-stroke Superbike proved for the first time to be more powerful on the same dyno than the NSR500 two-stroke GP racer (running this season on unleaded fuel for the first time), with more than 4 bhp more than in 1997, meaning upward of 184 bhp. Wow! I had a graphic illustration of the relative performance of the two bikes at Moteg;, when Shinichi Itoh, riding Mick Doohan's SR, obligingly outbraked me into the hairpin leading on to the downhill main straight. Okay, I guess that didn't take much effort - bu t once straightened up and flying right, I can twist the wrist in a straight line as well as any works rider, and it was really remarkable how the GP two-stroke only inched away from the RC45 - and that was probably down to my, er, extra pounds compared to skinny Shinichi-san, quite apart from the 70 more pounds the su perbike is required to weigh under World Superbike rules. It was impressive. And that's exactly what the RC45's power delivery is. Whereas the NSR500 comes on strong in Screamer guise at 9000 rpm and is all done by 13,000, tile superbike pulls hard from as low as 7500 rpm out of either of Motegi's chicanes, when the second injector on 'each cylinder kicks in sequentially. From there to the 12,000rpm mark there's a lovely spread of usable power, before engine speed suddenly picks up like a two-stroke, and suddenly the big green light on the dash is flashing at you to tell you it's time to hit the gear lever and shift wide open upward, sending the trademark drone of the V-four engine an octave lower. For test purposes, the shift light is set at the same 14,750-rpm mark in every gear, but in race use it flashes at different revs in every gear, encouraging the rider to maximize engine performance all the way through the gearbox. The fact that the engine is so unbelieva1;lly eager'-revving at high rpm means you're .changing gear almost as often as on a two-stroke, in which case you can't help noticing that the shifting is not as light and precise as it was a year ago. Honda has probably had to undercut the pinions more to cope with the extra power on tap, and this actually means it's bett~r .not to use the speedshifter in the bottom three gears but to change up normally, which avoids gear shock unsettling the back end when you're leaned over exiting a turn. The gearbox is still, moreover, not extractable, so changing internal ratios once at the track is time-consuming and difficult. Addressing that problem will surely be high on Honda's list of priorities for the all-new superbike they'll be launching a year from now in time for the year 2000 World Superbike season and contrary to much uninformed specula tion, HRC confirms t.his will be another V-four <1esign, not a V-twin based on the VTR, as rumored. Preparing for the new bike was the main reason for one of Honda's two main chassis cIlanges on the '98 RC45. The other was less obvious, in tile form of altered bracing to the stock chassis to make it less stiff from side to side. This was to impart more feel to the rider, and hence, together with the all-new internals for Showa's 43mm upside-down forks, to make it more responsive. But a more obvious change was the adoption of a twin-sided swingarm used at Philip Island and every race thereafter, which Nakamoto-san says is part of the research and development for the nextgeneration Superbike, which will definitely be fitted with a twin-sided rear end instead of the stock RC45's single-sided swingarm. The double arm allows up to 5mm of side-to-side flex, while being more resistant to twisting, and thus stiffer torsionally, than tile single-sided arm. Tough for Elf, which won't receive any more royalty payments on this - but better for HRC's race mechanics, who won't have to grapple any longer with the intricacies of adjusting the bike for chain stretch or different gearing without messing up all the suspenSion and geometry settings via the eccentric adjuster. Since Phillip Island, where both Slight and Edwards raced with the mono arm after it proved a whole second faster per lap than the twin arm, HRC has thrown a succession of revised twin arms at the bike. By the time I got to ride, it was on version six, according to Nakamoto. "The twin arm gives better feedback and improved tire life because it has more feel when you start to slide the bike, so you can use a softer tire for extra grip," Slight says. "It also makes the bike more stable through really high-speed turns, like at Monza, but it doesn't ride bumps so w~1I as the mono arm, so we still need to work on that." Both bikes I rode at Motegi had twinsided rear ends, bu t the endurance bike rode the new track's only significant bumps, between turns one and two, much better than the Castrol machine, which shook its head and flapped the bars when it rode over them with the power on, didn't hold a line so well under acceleration, and didn't turn in so easily. Thi is obviously down to rider preference, expressed via setup. I know from riding Slight's bikes for tile past six years that he likes a very balanced machine, with a lower rear ride height than other riders, which alters the weight distribution and geometry, witll the result I experienced. It's all a question ot choice. Slight had a different hang-up in '98. "Brakes are my biggest nightmare this year," he told me at Assen. "There could be more. bite, but that's not the main headache, which is that they're continually sticking on. That was the main problem at Kyalarni and Laguna Seca. You'd brake hard into a .tight corner, turn it and dial up some horsepower - and you'd lose the front, because the brakes are locked on." Nakamoto is aware of the problem, which he says came about because Brembo introduced a four-pad caliper this year, witll bigger pistons to deliver more bite. . "We obtained increased braking power," he says, "but the tapered edges on each pad have a propensity to kick out and lock on. We ran a modified version on the endurance racer which worked better, with Jliston location changed and taper better. But even this is still not perfect, plus feel of braking is not so good and brake pressure is not constant. This needs much work to inlprove for next season." Well, Honda isn't alone in this, as fellow Brembo user Troy Corser confessed to me when I rode his bike - but while I can't say I had the brakes lock on for me at Motegi (which was just as well, but obviously I was not squeezing hard enough!), there didn't seem to be the same bite, modulation or sensitivity that I remember with previous Brembo packages. One notable improvement, however, is the Honda's stability under heavy braking, which at Sentul a year ago had me arriving at turns with tJle pads knocked back, because the front end had been moving around so much. This year's bike is much better bel1aved - not because of any difference in road sur- • face between Sentul and Motegi, as Nakamoto said when I remarked on this to him, but because of the more composed handling of the new controlledflex frame, plus improved suspension response from the new Showa ·front end (the rear shock is the same as in '97). This improvement is so notable that Honda has removed the CTS Iinkedbrake system borrowed from the CBRllOOXX with which Aaron raced many times in '97. This was only fitted in an effort to cure the instability under the heavy braking his riding style calls for. It's the one very noticeable step forward in what was already a truly awesome motorcycle - the closest thing in superbike racing to a well-mannered four-stroke GP racer. Which brings it all down to 1999, the RC45's last year in action and perhaps, too, Aaron Slight's vi it to the Last Chance Saloon in an effort to win the World Superbike title that has eluded him for so long. 'The Duca ti's a masterpiece of development using lots of nice parts, from a production base that has a built-in 250cc advantage," says the Kiwi, "whereas the Honda is an engineering feat that's the product of a company which is technically more astute. For me, the greatest reward I could ha ve is to bring the World title to the people who most deserve it, who are the HRC engineers that created this engineering work of art and tile team of mechanics who bring it to the tart line. It's up to me and Colin to do the' business on their bellalf, and I'll be doing my level best in '99 to bring the World title back to Honda, where it belongs." That's telling them! _

• Cover