Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/128324
Capacity Changes Explained T he M5MA. the Grand Prix manufac- facturers are a lot closer to the sport than in engine. the shorter the time you have avail- turers association, has announced the car world , and we do not want the tech nology to be restricted." The reduced capacity limit in itself does not mean that we will see a reduction in horsepower. Indeed as advanced technology able to compress, ignite and burn the mix - that it wants the Grand Prix Commission . the guardians of the MotoGP rulebook, to reduce capacity limit for MotoGP to 900cc from 2007. This, it says, is not intended to slow things down, but is intended to try to prevent ever-increasing speeds. The MSMA has also confirmed it wants new weight limits to go with the reduced capacity. Although there has been a small rearrangement in weights . such as allowing gas tanks to remain on the bike while they are being weighed, the new proposal changes the whole structure of weight levels for different engine layouts. Twin cylinders are to have a lower weight limit than any other category, 133kg (292.6 pounds , down I I pounds) ; triples are 140.5kg (309 pounds , up 5.5 pounds) ; fours remain almost unchanged at 148kg (325.6 pounds) ; but fives go up to 155.5kg (342.1 pounds); and six cylinders become 163kg (358.6 pounds). There has never been a real opportunity to build a competitive tw in before, as it has always been thought that the superbig bores of a 990cc twin just couldn't make enough power to be competitive. However, with this decrease in capacity and with a small weight advantage, the twin suddenly becomes a real alternative . Meanwhile, the additional weight penalty on a six cylinder makes this configuration even less likely . The 22ml fuel (5.72 gallons) capacity limit for 2005 has been confirmed , but it is proposed that there will be further reduc tions in the future . Takanao Tsubouchi, the secretary general of the MSMA said, "We have a choice of reducing the capacity or limiting the tech nology. In the motorcycle world, the manu- eN becomes more common in the motorcycle world, a fairly small increase in the revs the engines work at could lead to the smaller engines quite easily matching or beating current power outputs . Current top MotoGP engines are making in the region of 240 horsepower. With current technology, the theoretical maximum would be somewhere in excess of 300 horsepower ifthey fully adopt Formula I levels of technology. Motorcycles, though. have different power requirements from cars. Motorcycles have very small contact patches by comparison . so there's a need to control the power very carefully This means that . they might actually need more technology than is seen in cars to allow them from make the best use of the smaller engines. The simplest way to look at an engine is to think of it as an air-pump - the more air that gets pumped through , along with the correct fuel mixture, the more power it will make. If we have a certain capacity, we should make more power if we can rev it up some more. There are limitations, however. Pistons have maximum safe speeds. and very few engines allow their pistons to exceed an average of 25m/sec . for any period of time. As a result , engine design is always evolving. bores typically are getting larger and the strokes shorter, allowing more and more revs for the same piston speed. Designing engines with bigger bores requires a lot of development. The bigger the bore, the more difficult it is to ensure that all the mixture will burn on each revolu tion, and the faster you are revving the rpm . By comparison. the most extreme MotoGP engines are probably the Apriliaand the Ducati, with both havingtheir roots in F I technology, albeit a few years old. Although the factories will not confirm any specifications, it's estimated the bore-and -stroke ratios of both engines are close to 2 to I. Brake Mean EffectivePressure isthe standard by which engines can be compared for efficiency BMEP usually drops as the revs . rise. It is thought that at around 19,000 rpm the current BMW FI engine is operating around a fantastic 14 Bar. Calculate that out and it means that a 900cc triple, built from the same engine at the same 14 bar and at the same 19,000 rpm , should produce the peak of around 300 horsepower. Ducati will not confirm anything about its monthly Personal Watercraft Illustra ted, and the continued str ong enthusiasm and growth w ith Mota K;ds , it is time to commit a to plevel person to the role of our magazines' cir- culation growth and development," Klinger said in a press release . "We're hitting on all cylinders right now and pleased to add the talent and personality of Kirk Holland to our top-notch staff." "The quality of CN Publishing publications has always been excellent, " said Holland. "I'm excited to help develop the huge potential audience for the ir publi- nization's promotions manager. director of commun ications and most recentlyas the IjSB,A;s executive director. "With the comparison, the rest of the engine is fairly simple. There are severa l ways of describing an engine. We are used 10 quoting the bore and the stroke, but what we should do is quote the bore-stroke ratio. The performance capability of an engine is usuallydefined by its Brake Mean Effective Pressure (BMEP for short). BMEP is the measure of the engine's efficiency, and it is difficult to maintain a con stant BMEP as revs rise. It is easier to have an efficient inlet/burn/exhaust process if you have all the time in the world, but a BMEP of over 13 Bar would be very good in any engine using over 10.000 rpm . Current FI engines, the most extreme in motorsport, have bore-stroke ratios of 2.25 to 2.5 to I, i.e.: bores of 98mm and strokes of 39.8 mm . With a maximum mean piston speed of about 25 meters per second , this leads to maximum revs just under 19,000 cations and max im ize the opportunities for circulat ion development. Cycle News. Mota K;ds and Personal Watercraft Illustrat ed have unique acce ss to a lot of resources in the powersports recent extreme makeover of Cycl News, the e r eturn to growth in the wa ter - craft market and upgrades to our Kirk Holland 10 MAY 19, 2004 • CYCLE NEWS closer to the Formula I extremes with a bore-stroke ratio of 2.215. Ifwe then revved the engine to the same piston speed of 23.5 meters per second , it would be revving to 18,000 rpm . If Ducati can maintain the BMEp, then it will produce exactly the same peak horsepower, but at higher revs. The trick, of course, is to maintain the combustion chamber efficiencyand therefore the BMEP as the revs rise. This is not world-leading stuff. as most Formula I engines rev that high - but it would put bikes closer to Formula I than ever before. The bikes would certainly need more of the "Ride by Wire" technology to be able to produce useable power - and this seems to be what the MSMA wants . In cars the "Drive by Wire " technology is used everywhere from everyday Citroens to top-of-the-range BMWs as it is used to lower emissions and improve fuel economy . This technology hasn't made its way to motorcycles yet, but it's likelythat manufacturers will have to meet ever more stringent emissions regulations on the road, just like cars. Developing this technology at the MotoGP level first makes sense. Since motorcycles react differently than cars , there is a lot of learning to do . It also makes it easier to "sell" to the public if the racers also use it. Nell Spalding All Pearson: David and Russ top Jericho H&H Publishing Hires Holland Cycle News Inc. publisher Mike Klinger has announced the appointment of industry vet e ran Kirk Holland to the com pany's newly created position of circulation development manager. Holland's responsibilities include overseeing the circulation growth for all CN Publishing Group titles and properties: Cycle d News, Mota K; s and Personal Watercraft Illustrated. Hollandis a highlyrespected and prominent figure in the powersports rnarket working 14 years at the Inte rnational jet Sports Boating Associa tion and two years at Edgell Expositions (now Advanstar Communications). At the IjSBA, Hollandheld positionsas that orga- ture. The most difficult part of a motor to develop therefore is the cylinder head. By engine's internal specification. but an edu cated guess says the engine has a bore and stroke of 86 by 42.6mm. Turning at 16,500 rpm, this engine produces about 245 horsepower with a BMEP of 13.75. At 16,500 rpm this engine would have a piston speed of 23.5 meters per second. If Ducati made the engine into a 900cc version with the same bore but shortening the stroke. It would be able to use slightly modified versions of the same heads and would move industry. I'm also very familiar with the experienced and talen ted staffat CN Publishing I can't wait to ge t started." 40th Anniversary wasaki Team Green's David Pearson edged out his cou sin K: uss Pearson to w in round five of the AMA National Hare & Hou nd Champions hip Series in je richo, Utah, on May 8. At one point, David held a commanding lead ove r Russ, on the Racing Montclair Yamaha/Zip-Ty YZ450F, but Russ made it close at the end after closing to within about 10 seconds of his KX500·mounted cousin by the time the checkered flagcame out . It was David's second win of the series. Two of the series' other top ride rs had little success in Jericho . Neither Kaw asaki Team Green riders Brian Brown nor Destry Abbott finished the race. Brown crashed out with a damaged bike, while Abbott dropped out with mechanical pro blems. David Pearson pasted his second National Hare & Hound win in a row.