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/128334
MotoGP Tech Update: Honda Goes Up A Gear! getting full powe r o ut of such a set up wou ld be to fit se parate pipes to each cylinder. We have seen a lot of exhau st pipe changes this year, and this late st one fro m Honda is very similar to the five-inta-four system debuted by Proto n a few races ago. It may be that Honda has not changed the fro nt cylinder pipes beca use of the very tight spacing unde r the engine . But it might want the spread of power that you can get by tuning several cylinders differently - top end po wer from the back pair and cen ter fro nt cylinder and strong midra nge fro m the two -into-one fitted to the outer cylinde rs of th e front three. Hon da typically gives its numbe r-one ride r the first go on anything new. Looking around the bike s o f its to p r iders at Sachsen ring, there were big welds where new swingarm pivot positions had been welded in. Just like last yea r, th is means that Barr os has had a new chassis with the changes (which would only be a millimeter o r so) fo r a few races and that the rest of th e chass is will be converted as the ride rs dec ide if they like the mod ificat ion. Nicky Hayden , 5et e Gibemau and Max Biaggi all had on e bike each with the new setu p. Most riders seemed to prefer the new chassis and were using it most of the time. The swingarm pivot position is extreme- Honda's new e xh aust system o n Alex Bar ro s' V-five showed up for the first time in Germa ny; ditto for a ne w swing arm p ivot for Nicky Hayde n's Repsol Honda. T he tec hno race heated up yet again at 5achsenring this past weekend, with H onda coming up with a new engine setup and exhaust configuration (or Alex Barro s. It also issued three of its other to p ride rs w ith one mod ified chassis each . The engine and exhaust were tested in Japan on ly two days prio r to the event and were flown in to be fitted to the Barros bike the Th ursday even ing before practice. The two rear cylinders have a new exhaust sys tem to replace the two-into-one pipe previo usly used on the rea r cylinder. The new pipes loo k very similar in co ncept to the one previously fitt ed on ly to the middle cylinder at the fro nt. Exhaust systems are used to help the engine s make power, and a correctly designed exhaust can provide a low-pres sure pulse timed to arrive just as the exhaust valve o pens, helping the engine ge t rid of the exhaust gases q uickly. The length and diamete r of the pipe, the shape and size of any megaphone on the exhaust and the decision to connect the exhaust to any other cylinders all change how well each system and engine combination works . T he pipe manufacturer can choose to focus a big power gain in one place o r to spread the same pow er over a broader area. In any com bination pipe, be it four-into one or tw o-into- one, the manufacturer is using the exhaust gas press ure fluctuations 8 fro m o ne cylinder to try to help the ot her cylinders. Usually this is done to boost the midrange, and if you get it right, you can get extra power without losing any from the top end. In Honda 's case the decision to fit ind ividual pipes to the two rear cylinders means that the exhausts can be tuned more accurately to provide a power boost over a very specific area of the power band. The effect is similar to focusing a camera lens - getting one small becoming apparent is that most teams have adop ted a firing order tha t places the pulses from pairs of cylinders only 60 degrees apart - close r together than the 75.5 degree s of the Ho nda . Th e 3D-degre e change that was required to get the Ducati working was clear- interesting to see how fast we see similar engine and exhaust combinat ions on ly audible. If Honda has decided that the 60deg ree idea is better, it would have to tw ist the crank just I5 degrees, not so easy to hear. But if it has do ne this then the best way of Gibe m au and Biaggi's bikes as it appears that is whe re the new parts can do the most fo r Ho nda. Neil Spald ing area exactly in focus and the rest blurred. At first glance, the decis ion to fit these pipes for t he Sachsenring seems strange, as the old system looked mo re suited to producing mid range power, which should help in Sachse nring's tight comers. The new exhaust wo uld be better suited to a top -end boost. But the 5achsenring is very, very tight, and a lot of th e lap is spent with the bike on its side . In those situatio ns a soft reaction fro m the throttle would make the bike easie r to contro l, so maybe H onda hasgiven Barros an easier-to -use powerband for the twisties and even more go for the straights. In addition, Honda has managed to squeeze in an extra test, and if there is an improvement it has given itself enough time to produce a similar setup for all the top Ho nda riders by Brno. A second theory is that Honda has do ne a mini big-b ang jo b on its e ngine . Most MotoGP teams have ado pte d different firing o rders on their engines in the last year, and mo st we re copyi ng Ho nda, but w hat is JUL 28, 2004 • C Y CLE NEWS Y ly important to th e hand lingof the bike, and o n so mething as fine-tu ned as a MotoGP bike it affects the way the chain pull makes th e bike mo ve aro und. Last yea r 's mo dificatio n was to make the chain pull the rear wheel do w n onto the ground during heavy braki ng. 50 far this year, Honda won 't even admit it has changed something and will not tell us which way it has moved the pivot . Ho nda usually has severa l races with new stuff on its top rider 's bike - it will be 40th Anniversary