Cycle News - Archive Issues - 1990's

times show we're faster through turns on our su permonos than ei ther the superbikes or supersports we share the World Superbike Championship race program witl1. But I like a brake with lots of bite, where you can leave your braking as late as possible knowing that you're going to get it stopped, rather than hoping you might. That's what the sintered pads in the Slight Honda deliver - lots of feel, but immediate stopping power (though not as much as with cast-iron discs), and reduced weight transfer with better stability under braking, thanks to the more balanced chassis setup. People talk about Slight as being a stop-and-squirt kind of rider, but that's simply not true. Comparative section times throughout the season showed that he was consistently one of the three fastest riders through medium-to-fast hrrns (Corser and Pier-Francesco Chili, in case you wondered); even though he brakes very late, deep into the apex of a turn. But the trick is tha t he carries lots of corner speed while doing so. Trying to emulate the maestro at Phillip Island revealed how much more stable and better balanced Aaron's bike is on turn-in. It gives you the confidence to brake deep into the apex before dropping it into the turn and powering out. Slight's bike felt a good bit less nervous than his teammate's Honda, not just in comers but especially down the straight - presumably because it doesn't squat the rear end so much and lighten the front. It also was slightly better on traction, though it still liked to slide the rear wheel a little in some turns.. But sliding the back wheel is all part of life's rich pageant when you race an RC45 - ask Miguel DuHamel - and once you've learned to do so in a smooth and controlled fashion, then you can start to get results with the bike. That's almost certainly the reason for Slight's success with the Honda. Three seasons into riding it, he knows its tricks better than anyone else, and has learned how to strike a balance between aggression and smoothness, to combine a fluid riding style with going in deeper and coming out harder. He's also adapted his natural riding stance to suit the bike, staying low over the tank and shifting his body weight around to suit every situation. In his debut year on the RC45, Fogarty found it tough to adapt his naturally brusque and aggressive style full of sharp, decisive body movements, to this bike. Remember, his wins all came at smooth, fast circuits which rewarded judgment and bravery in terms of maxing out comer speed, rather than at tight tracks where the Hondas are still second best - third, actually; Edwards' Yamal1a is now a better ride on twisty circuits or anywhere with bumps, as Albacete and Phillip Island proved - however, Phillip Island also proved that Slight knows how to ride around these problems, while reaping the benefits of the F-spec RC45 motor's now class-leading power . delivery and turn of speed. With Ducati having played its last hand of cards in the 916's Last Chance Saloon by increasing engine capacity to the 1000cc twin-cylinder limit, and hitting piston speeds on a par with current Formula One car technology, it could just be tha t 1997 will finally be Honda's, and especially Aaron's, year. If at first you don't succeed, try, try - try again? With Kocinski and Fogarty swapping seats, it'll be interesting to see if John Boy can adapt himself better to the RC45 than Carl did. One thing's for sure, it'll be great watching him try. a HONDA'S INTENSIVE QUEST TO REGAIN WORLD SUPERBIKE SUPRE- macy in '96 with its new Slight/Fogarty dream team meant intensive work on the 90-degree V-four RC45 engine package over the '95-96 off-season. The 7-spec engine Aaron used to clinch his third place in the '95 title chase was upgraded to an 8spec for 1996. This duly delivered a debut victory in the Daytona 200 courtesy of Miguel DuHamel, in a race graced by every other World Superbike factory team, including the Promotor Duca ti that would eventually take the title: lookin' good .... HRC's Syuhei Nakamoto, chief development engineer for the RC45, explains the continued evolution of the fuel-injected, four-camshaft, 16-valve Honda motor. "The 8-spec engine was mainly a refined version of the 7-spec version, but with extra attention paid to reducing friction still further," he says. "We used the same cam profiles but altered porting in the cylinder heads, which delivered improved gas flow and increased topend power by 3 bhp - still at 14,750 rpm peak revs." At this stage, Honda was still using the so-called adjustable air-funnel system on the PGM Fl EFl, its version of a variablelength inlet system operating in on/off mode at 12,700 rpm, which used a servo motor to lift the venturi clean off its 46mm throttle body, thus effectively shortening the inlet for increased top-end poke. This allowed Honda to fill in the hole in RC45 midrange power without sacrificing peak output - though the AMA's ban on such systems (which all manufacturers except perhaps Suzuki are known to be experimenting with) meant that DuHamel had to run without it at Daytona - not a problem on such a top-end track. The Castrol RC45s ran with the 8-spec motor for the first half of the '96 World Superbike season - delivering a race victory for each rider in the third round in Germany, plus another for Carl at Monza - until SentuJ, when the debut of a radically revised version known as the F-spec underlined how hard HRC engineers had been working in the meantime. "Before, with the 8-spec the Ducatis still had a definite topspeed advantage, so we could only slipstream them - we won our three races because they made mistakes and we didn't," Slight says. "But from 5entuJ onward with th~ F-spec, for the first time we could now pull out and pass them. It was a big improvement." Nakamoto explains why: "Everything change," he says. "We found another four bhp on top-end power with the F-spec engine, with more attention to reducing friction, and many new parts." . These included a reshaped, even lighter two-ring piston delivering a higher 13.2:1 compression ratio; modified cylinder heads with altered cam profiles and single springs instead of double ones for the titanium valves, the specifications of which were also changed; a redesigned one-piece crankshaft and internal modifications to the crankcases (perfectly legal under Superbike rules); revised titanium rods; and a different exhaust system for more top-end power, with two 2-1 separate pipes rather than the 2-1-2 combined system previously used. But though what was essentially an all-new engine inside delivered even more power at peak revs, it also accelerated faster and, most important of all, had much better midrange power. In fact, the midrange was so improved that Honda stopped using the variable air-funnel system - there are no more holes in the powerband for it to fill in. Having changed EFl settings slightly at the start of the season, Honda keeps the same ones for each track, says Nakamoto-san, but they did experiment a lot in the first few races with variable curves for the separate ignition system by using different EPROM chips. No traction control yet, but Honda admits they're working on it and plan to have something in operation next season, to help cure the wheelspin that's a constant factor on tile RC45. The gearbox is a carry-over from '95, but the design of the friction plates on the 9-plate wet sprag-type clutch has been cllanged to deliver an easier action so as to improve starts with the hydrautic opera tion. "Getting the power to the ground has been a problem for both riders," says Fogarty's race engineer Nick Goodison. "They feel they have to wait for the back end to hook up before they can get hard on the gas out of a turn, and there's a variety of factors that cause that - transmission, engine characteristics, suspension, lots of things." Hence development this winter focused on confronting this problem: Honda is working on electronic launch control, Michelin on tires which deliver good grip without sacrificing corner speed, and Showa on a radical new suspension design (almost certainly using nitrogen or another type of inert gas) which. will allow them to fine-tune shock and fork settings on the bike far quicker by using external valves, rather than having to dismantle the units on the bench to change internal components, as at present. The ban on prerace testing at circuits used for World Super- . bike rounds being introduced for '97 will make this all the more critical, because teams won't be able to spend two days at a venue before each-race dialing the bikes in for that particular track - a move that will undoubtedly affect the four-cylinder bikes much more than the Ducatis, which are far less critical on suspension and chassis setup. Honda concentrated on engine development on the RC45 this season, keeping the same basic chassis configuration as in '95, but with a lOmm shorter swingarm on both riders' bikes in order to try to improve traction by putting more weight on the back wheel and increasing weight transfer under acceleration. After the experiments with an adjustable steering head in '94, which allowed them to effectively alter the engine position up and down or back and forth relative to the wheelbase, they went back to the stock frame setup in '95 and have concentrated on making that work to best effect. That meant giving Honda's Showa suspension partners a wakeup call by testing Ohlins forks and shock at the start of the year in order to set a baseline. Showa responded with components that were heavily revamped internally and seemed to perform better, though are still very critical on adjustment - a 2mm difference in ride height can make the difference between the bike being ridable or an animal, say Castrol Honda staff members. Honda did chip away at reducing weight still further, though. So effective was the weight-loss program that the Castrol Honda team volunteers to carry a TV camera in every race, so as to ballast the bike to beat the 356.4-pound weight limit. Without it, the RC45 is two pounds underweight, admits Nakamoto-san. It was also for this reason that a steel exhaust was adopted from Sentul onward, rather than the much costlier titanium one used until then. Weight distribution is still 54/46-percent even with the shorter swingarm - but it's how the weight is carried that counts. The RC45 still apparently has an inherent problem with the relationship of the center of mass to the center of gravity, aka the polar moment of inertia, thanks to the V-four engine configuration and its far-forward location in the frame. This causes the front end to get unloaded if you hit .a bump in the middle of a turn, pushing the front tire sometimes beyond recovery - unless you back off to let it recover. Both team and riders, especially Aaron Slight in his third year riding the bike, have learned how to work around this, but it makes suspension setup and tire choice critical. Get one or both wrong - like at Donington or Brands Hatch or Albacete and the Honda riders are struggling. The fantastic perfom1ance of the RC45 engine in its latest Fspec form - achieved without sacrificing Honda's legendary reliability - only goes part-way toward curing that. Now HRC needs to focus on increasing corner speed with the bike, Slight says. '1 thought we'd reached the limit of development at the end of '95," he admits, "but this year Honda has found even more power and made the bike nicer to ride with better midrange, and lap times have dropped all round. "But the Ducatis have only kept up with us by running on the edge of reliability - look at all the engine blowups Corser had this year. Plus, before they could keep their advantage by just increasing capacity a little, but now they've reached the limit. I'm convinced now we can go even faster, but for that we need more corner speed and tha t's the area the engineers in Japan will have to work on for '97. But now we have a bike that can run with the very best." - 19

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