Cycle News - Archive Issues - 2000's

actually revs 1000 rpm lower). However, think back to IV coverage of the GP races this seaso n and re member w here you've seen Bayliss and Capirossi pow ers liding the Ducati and laying dar kies of rub ber with the front wheel countersteering at 45 degrees to the rear. That's right - on third and fourth gear corners. And that's where I could feel the rear starting to drift on me at Valencia - aroun d the long, long, fou rth-gear (we ll, for me!) left swee per leading down to the last tu rn. No pretense at laying any rubber, but the Ducati surely has awesome acceleration in almost any gea r at almost any revs, w ith that legendary co nnecti on between throttle and rear wheel. The well-mappe d Marelli EFI makes riding the bike much less daunting than its fire-breathing first impress ion leads you to expect - though there's still a great sense of power and performance at almost any revs . Yet the tubular steel chassis, wh ich gets all that power to the ground , seems more than stiff enough to cope wh ile delivering loads of feedback, much like on the desmo V-twin 5uperbike. It feels better balanced than Neil Hodgson's 999 World 5uperb ike that I rode back in June at Misano, witho ut such a feeling of high-speed instability or it be ing so crit ical w here you placed your body weight . O n the Desmosed ici you just need to hold on tight w hen you twist that wrist to make sure you don't get blown off the back. The extra grip from the wide r 3.6-inch front wheel probably contributed to a greater sense of security in terms of keeping up corner ing speeds than on the Superb ike. It sto ps feeling like a point-and-squirt motorcycle after a couple of laps of gradually building up your co nfidence , and you stop being so int imidated by it in t urns . Well, mostly The Ducati requires a fair . bit of muscle to make it steer, because this is a pretty physical motorcycle to lift from side to side . in spite of what seems a lowe r ce nter of gravity than I expected. Due respect goes to the pint-sized Capirossi for his racewinning exploits aboard it. Maybe his bike would have been easier flipflopping through the Valencia infield than Bayliss', with the steeper head angle and more A co m p uter gene ra tion o f the Des mosed ici V-four. Cla imed o ut p u t is ov e r 220 ho rsepow er a t 16,0 0 0 rp m. Tellin g So me, But Not All Ducati Co rse 's creation o f the Desmosedici was accomplished in typic ally focused , fast-forward fashio n. And it should be noted, it w as created simultaneously w ith th e alii-new 999 F03 Superbike. Corrado Cecchinelli, technical director of the Ducat! Marlboro GP team and before that the archi- tect of Troy Bayliss' World Superbike crown and a hatful of World Superbike Manufacturers' titles, takes us through its evolution. "We spent a lot of time during the winter of 200 1/2002 examining different computer models for the engine, all on our CAD system , just thinking rather than making or test ing anything. mainlyaimed at first at wo rking out what format the engine should take, " says Ce cchinelli. "I think we made good use of our Superbike experience and tried to make the bike as simple as possible, because that seemed the right way to be able to be competitive very soo n, as well as making it easier to work on it physically especially at the race track. On the other hand, the Desmos edici is so simple that it will , need to be redesigned quite substantially in order to be any better - but that 's okay, because this way, we got to a good level very fast." Initially, Ducati considered making an ultratwin, a no-holds derivative of its successful 90-degree V-twin desmo Superbike . That platform would have had obvious marketing benefits. but it wasn't judged likely to produce enough power to be competitive - even with the 22-pound weight advantage for tw ins and triples against fours and fives under MotoG? rules. After briefly considering an oval-piston twin, this was also rejected on the grounds it would be too expensive and complicated and it would also forfeit that weight advantage. "We design all our bikes wit h the idea of eventually supplying them to our customers in one form or another," says Corrado, "and while there are no firm plans to bring the Desmo sedici to market just yet, the technology in it will for sure form the basis of future streetbikes. That couldn't have happened with a bike with two oval pistons, 16 valves and four con rods ... Discarding the idea of a triple as a) not a Ducati format and b) too closely linked in MotoGP with keen rival Aprilia, that left a four-cylinder engine as the next opt ion, and after doing a lot of work on a 70-degree V-four layout (which would have bee n ve ry compact), it was eventually decided in December, 200I, to opt for a four-cam, liquid-cooled. 16-valve 9B9cc 90-degree V-four. Even employing an extremely short-stroke layout as Ducat i admits the Desmosed ici does (in pursuit of higher revs than any other bike on the MotoGP grid, even the pneumatic-valved Aprilia triple) thanks to careful design work , the V-four engine is only a little wider than a v-twln , though the heavily oversquare dimensions and tilted-back cylinders do provide space to install the motor in one of Ducati's trademark tubular steel frames without front wheel clearance problems under braking. But the whole concept for the motorcycle is one in which the engine was designed as a fullchassis component, FI-style, says Cecch inelli, in a way that began in motorcycles with the Cosworth-engine Norton Challenge a quarter-century ago yet has been very rarely adopted by anyone else since then . "O ur 'whole-bike' concept sees the front suspension mount to the frame , the frame to the engine, and the rear suspens ion also to the engine, with the swingarm pivoting in the crankcases unsupported by the chassis, as it is on our Superbikes, just to save we ight," he e xplains. "We had the chance to design the engine and chassis together and could calculate that the ext ra weight needed to make the 36 JANUARY 14,2004 • CYCLE NEWS engine strong eno ugh to support the swingarm on its own was less than if we'd had to add an extra section of chassis to do the same job. Also, it makes the bike narrower this way between the rider 's feet, which helps reduce frontaJ area. We paid a lot of attention to aerodynamics and worked with Alan Jenkins in the Ferrari wind tunnel to optimize this. As it is, this creates a very stiffstructure which is needed to put so much power on the ground ." How much is that? Well, Ducati is very coy about this, quoting "over 220 horsepower at 16,000 rpm" to anyone who's interested - but with both Honda and Yamaha admitting more than 240 horsepower at the gearbox on their bikes, it's obvious that the red Italian rocket is push ingout around 250 hp at the cou ntershaft sprocket. Ducati's original intention was to produce a double V-twin called the "Twin Pulse" V-four, with a flat-plane lBO -degree crank delivering two-up throws. whose Big Bang delivery would in theory enhance tire grip and promote traction . However, just to be on the safe side , Ducat! Corse also developed alongside this a more conventional cruciform design with 90·degree firing, just like gener ations of Hondas with a similar 90-degree V-four architecture , and it was this "Four Pulse" format that was eventually selected. "We gave all three of our riders the chance to test both types of engine, right up until our tests here at Valencia in December, 2002," says Corrado. "But we didn't see any real advantage from the Twin Pulse compared to the 'Screamer, ' so with the higher vibration levelsand increased friction, and likely reduced component life as a result, it made no sense to pursue this. Therefore we chose the configuration we have now. It sounded very unusual, though !" However, running an ultrashort-stroke engine in pursult of more power at much higher revs only works in conjunction with nonco nventional valvegear; otherwise you get valve float and sundry other disasters occurring if you reta in regular valve springs. This mean t Ducati had a choice of either taking lessons from its Ferrari neighbors in developing an FI-type pneumatic valve format or else adopting its own signature mechanical system of positive valve operation, a.k.a. desmodromics. "Truly, we never considered using pneumatics," insists Cecchi nelli, "because we knew from the very beginning that the desmo would wo rk, thanks to our reliable simulation programs - so why not follow our traditions? AnY'Nay, bikes aren't like cars, where the engine is turn ing close to maximum revs most of the time . With two w heels you use part-throttle a lot more , so the advantages of pneumatic valves are much reduced , whereas our experience with desmo has shown there are many advantages in midrange and low rpm . too ." The 90-deg ree V-four engine doesn't need a balance shaft because of its perfect primary balance, and the four titanium connecting rods sit on a plain-bearing forward -rotating crankshaft, with four titan ium vatves per cylinde r set at an extremely flat included angle and operated by twin overhead camshafts (each with eight lobes on them for opening and closing the valves - there are no valvesprings - driven directly off the crank via a train of gears up the right side of the engine). An intermed iate gear drives the water pum p positioned between the Vee of the cylinders, as well as the twin spur gears, one each bank, which take the drive to the camshafts. The sandcast crankcases feature the same coppa bassa wet-sump design as the Testastretta V-twin Superbike motor, with the oil sup- 40th Anniversary

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