Cycle News - Archive Issues - 2000's

Gregorio Lavilla 5 A/stare Corona Suzuki GSX-R 1000 back wheel - even with the race-qual- impressive-looking Parabolica power- the approved manner, even if I didn't ity triple-compound tire Dunlop gave slide - though the first time it hap- quite manage to lay a Dunlop darkie me for the test, same as lannuzzo pened to me, I almost highsided when as permanent proof! Still, even spin- used to come in seventh in the race I took fright and backed off the throt- ning the back wheel, the Suzuki feels the day before. tle. But then the next time I was really controllable and responsive in Do that on the angle, and you'll braver and managed to control it on spite of (or, maybe, because of?) get a passable imitation of Lavilla's the throttle in something approaching being so powerful, with more torque TECHNICAL: fX]@[0(1[?D@(1@@ fX]fi]@@[? The immediacy with which Suzuki's new-for-'03 GSX-RlOOO has become the only serious threat to Ducati's current domination of World Superbikes, in this transitional year when the new breed of 1000cc four-cylinder models have to wear restrictors but the twins that have been doing all the winning don't, is thanks to an effective collaboration between the Japanese factory's race department and Team Alstare's in-house R&D operation, headed by the Belgian team's chief engineer, Bruno Bailly. Bailly and his boys were responsible for tuning the works GSX-R750 Superbikes Alstare had raced in previous years but until this year had never worked on a GSX-RI000. That changed last November, when to kickstart development of the new model launched at Intermot the previous September, Alstare stripped the two 164 bbp GSX-RI000 stockers sent to the team's Liege base, did some basic tuning work that included installing a set of Yoshimura pistons to the stock conrods and crank, then fitted its own 32.5mm restrictors beneath the 44mm Mikuni throttle bodies (up in diameter from 42mm from the first series GSX-Rl000) for the simple reason that the factory had as yet done no development work on the revised engine under the new restrictor rules only announced last December and could not supply anyl "On that basis, we got 185 bhp at the gearbox and around Nm lOS of torque," says Bailly, "but we couldn't rev it any higher than 12,800 rpm for fear of the stock conrods breaking. But then in January we got the good factory engines that we're running now, with titanium conrods, lightweight pistons and the works cylinder head. That's when we started getting competitive power - when we tested at Sepang that month, we had 198 bhp at 13,500 rpm, but also more torque, up to Nm 112 (82.66 ft.-Ibs.)at 10,000 rpm. Since then, we've done some more work ourselves, with new camshafts, altered porting, a revised exhaust and different intake lengths, and we're now up to 207 bhp at the gearbox, with Nm 117 (86.35 ft.Ibs.) of torque· but we have a big problem with torque delivery, which as you found out yourself arrives very brutally between 85009500 revs, irrespective of throttle openings. If Gregorio takes a bend revving the engine higher than that, he's OK - but if he hits this powerband in the middle of the tum, leaned over, he's in trouble with wheelspin. Though we've succeeded in calming things a bit via different camshafts and valve timing, we still have work to do on this - but what's encoun;ging is that, even with all this horsepower, the engine is still completely reliable. We run 2000km (1240 miles) on a set of valves, 1000km (620 miles) on the pistons, and the crankshaft and titanium conrods last 4000km (2480 miles), which is about six races. Fantastic, with over 200 horsepowerl "We've lost just two engines due to mechanical failure so far this year, for a stupid reason. One motor went at Phillip Island for reasons we couldn't decipher from the wreckage - until another one went on the dyno just before we came here to Misano. It was a race engine we were just running in slowly, so when it seized, we caught it before it exploded. It turned out there was a manufacturing fault on the rubber O-rings surrounding the valve pushers - literally, a ten-cent part costing thousands of euros in damage and two 20-hour days to repair it! Otherwise, the engines have been completely reliable." The factory race motor, now benefiting from ram-air induction, has had the balance shaft fitted to the stock GSX-R1ooo road bike removed and has been rebalanced to reflect the lighter billet crankshaft employed, fitted with titanium rods and two-ring forged pistons delivering a massive 15.8: I compressionl "You have to run it this tall because otherwise at high rpm, the restricted engine doesn't fill the combustion chamber very well," says Bailly. "Running even 14:1 compression, it flattens off at peak revs, so we have to use a higher ratio to compensate for this. We tried going still higher, in Japan, to 16.4: 1, but while it does accelerate better at taller revs, we've backed it off for security reasons. But for sure you couldn't run it this high without restrictors - there'd be massive detonation even with the very special AGIP fuel we're now usioIiL::J'his gives 1.5 bhp more than the gas they gave us at the start of1llfeYear, confonning to 2003 SBK rules, which are a bit tighter than last season." Chain drive (so no Kawasaki-style gear-drive conversion) is retained to the twin overhead camshafts located in the ported, flowed factory cylinder head, which has been further improved by Alstare's R&D team. The cams operating the oversize titanium valves, each fitted with dual springs and widened to 29.5mm for the inlets, and 25mm exhausts are Alstare's own design, with 10.5mm lift on the inlet valves and 9.4mm on the exhausts. The factory's ND engine management system has now been replaced by a Marelli ECU, which is essentially the same as that used by Ducati, with twin injectors per cylinder, one above and one below the single butterfly mounted in each 44mm Keihin throttle body, rather than the dualthrottle system featured on Suzuki's street motors, which has been retained on lannuzzo's lower-spec engine. "The twin throttles make his bike much easier to ride than our engine, with a smoother transition into the powerband and more progressive midrange torque," says Bailly. "But there's a small power loss entailed, so the factory wants us to stay with the Single-butterfly system, even though on some circuits it's a definite handicap." However, the stock throttle bodies, which must be retained for Superbike racing, do maintain the twin intake trumpets per cylinder, one short and one long, which are claimed to soften the torque curve - even if Bailly says Alstare is still experimenting with different lengths in order to fine-tune the power delivery. An Arrow titanium exhaust is fitted, devoid of the streetbike's EXUP powervalve system, while Suzuki's trademark semiextractable six-speed gearbox has wider pinions on the GSX-Rlooo transmission than the 750 to handle the one-liter motor's extra torque, which is the main reason the team are spared ratio swapping - Gregorio never changes the intemal ratios because the engine is so meaty and muscular in its power delivery. The ramp-type slipper clutch (similar to the one developed midway through last season for the works GSV-R MotoGP bike) is a departure from before, though, because unlike with the GSX-R750, which used a factory dry clutch, the GSX-RI000 must employ an oil-bath unit because the primary drive is so big, says Bailly - though lannuzzo's semiprivateer machine uses an Italianmade STM dry clutch whose perfonnance Alstare is monitoring. Judging by Vittorio's consistently brilliant starts, it works OK - at least off the line! The new GSX-RlOOO's twin-spar aluminum chassis is quite different from the older four-cylinder Suzukis' fabricated pressed-alloy frames, consisting of intemaJ1y-braced extruded sections that result in a stiffer, lighter structure, which also for the frrst time on a Suzuki incorporate an adjustable swingann pivot. In fact, the Alstare Corona bike is on its third chassis spec, says Bailly, with the original stock frame used for early testing at first replaced by a works chassis with heavy bracing around the steering head and pivot for the same swingann the team ran last season on the GSX-R750. But, while still basically a streetbike frame beneath a1l the extra metal, per Superbike rules, this proved to be too stiff, lacking the vital element of feel Lavilla needs when"he's powersliding out of turns at over 100 mph, so a third version was produced that has less bracing and more flex, so it can "talk" to the rider via the new swingarm and Showa suspension the team has now switched back to for this season. "Greg liked the Showas right away," says Bailly, "because they give more feeling than the WP suspension we used last year, and this is vital when dealing with the biggest single handling problem of all Suzukis, which is excess weight transfer, probably caused by having too much polar moment, with the center of gravity and center of mass too far apart from each other. But we're really happy how fast we can dial in the Showas for each circuit - this is a big ingredient in our perfonnance this year, together with the Dunlop tires, which have made a big improvement during the first part of the season, after being so uncompetitive against the Michelins at Valencia. Their hard work in Birmingham paid offl" With the 47mm upside-down Showa forks set at a 24-degree head angle and Lavilla usually opting for a little less than 4 inches of trail, the Suzuki scales in at 374 Ibs. half-dry - five pounds over the 369.6-lb. l000cc four-cylinder SBK weight limit "just to be on the safe side!" according to Bruno. This is split 52/48 percent front and rear and stopped by a pair of 320mm Brembo discs that, unlike the similar ones Ducati now uses, are unventilated, though still gripped by the same radially mounted four-pot calipers that are now fitted with a pair of bigger pads for more consistent heat dispersal than was possible with last season's four pad setup. Lavilla doesn't like the smaller rotors that Hodgson now uses on the slightly lighter Ducati, claiming that he needs the extra stopping power rather than focusing on speeding up the steering - although it was interesting that at my test Greg spent several laps on his spare bike assessing a set of those sexy-looking Braking Bat Flight (yes, really!) "margheritaO petal front discs, which while already lighter than the Brembos, now also have the swept surface scalloped to remove brake dust and deliver a firmer bite. OK - crunch time: How much perfonnance do those restrictors tllke away from the motorcycle that, even in strangulated fonn, is still the most"powerful Superbike ever to grace the grid? "Of course, we wanted to know that, tool" admits Bruno Bailly. "So, we've tested the bike without the'm, and with lower compression to avoid detonation but no other specific tuning, we got 10-12 bhp more but lost Nm 4-5 (3-3.7 ft.-Ibs.) or so of torque. That would make the bike easier to ride, less hard on tires and even faster. But it seems the twin-cylinder teams have the ear of the politicians, so in order to keep them competitive, we've ended up having to fit the restrictors. It's a pity - but even with this handicap, we don't do so badly!" Yes, but in 2004 it looks as if Suzuki won't have to worry about using them. than you can shake a stick at and a fabulously direct throttle control that epitomizes the legendary connection between the light-action twistgrip and the back tire. The Marelli EFI is perfectly mapped, and together with the Suzuki's twin-injector setup, this prevents too fierce a response when you get back on the throttle again for the exit of a turn. The predictable and forgiving nature of the Dunlop tires is a big element in this controllability; especially now it seems a matter of course that ttrey'li last the distance at most circuits. Dunlop has made a huge step forward in Superbike tire development this season, and the one-liter Suzukis have benefited from this better than any in taming their tremendous torque, which asks so much of a rear tire. This has allowed them now to match what was previously a significant advantage of the twin-cylinder bikes, in terms of the jump out of turns; riding Hodgson's 999 on the same day, same track, bracketed by my two sessions on the Suzuki, underlined that the Ducati is smoother low down off the turn, but the Suzuki's midrange power is more effective. Ultimately, the two are now very closely matched - but with the V-twin desmo still in unsrestricted form. Next season, it could be another matter. But another area in which the new GSX-RIOOO has gotten on terms with the Ducatis is in the handling department, thanks to the comprehensive chassis redesign Suzuki invested in for this year. Sitting on the bike, it feels smaller and narrower than the 44 AUGUST 27, 2003' cue I e n e vv sa

• Cover