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/126416
By Jim Gianatsis Photos by Charles Morey and Gianatsis The last 10 years of World Championship motocross have seen almost unbelievable advancement in the design of the bikes. This is particularly true in the 500cc class which holds the interest of most of the major manufacturers because of its status as t h.e .most diffiICUIt and most prestigIOus class. But as much as the bikes have advanced in design of their suspensions, engines and chassis, many of the riders still feel they have a long way to go. Suspension travel may have reached its limits around the !lOOmm mark, but nearly eve.ry factory team continues to redesign or modify their works suspe'!liions for better performan~e. The bik~ that appeared best handlmg on the killer Carlsbad track at the Bel· Ray USGP of Motocross were the newer designs, like Brad Lackey's Uni· Trak rear suspension Kawasaki and Roger DeCoster's works RN Suzuki with the radical trailing/leading link fork suspension. Roger's trick forks offer no real advantage over conventional slider front forks in either weight or improved handling geometry. Where Honda RC 4&0-79: Present Wortd Championship Series point leeder Graham Noyce I. on a pretty conventional RC worka bike which dlsplecea 460cc. Suspenaion trevell. 300mm lit eech end provided by work. Showe apring forka up front and Ohllna piggyback reservoir guloiIlIhoc:ka lit the reer. Americen teIImmllt8 M.-ty Smith looked good on a conventionel RC 2fiO. type bike with a Mugen 380cc cylinder kit. 32 they do out·perform conventional forks is in damping hwere the Ohlins. reservoir shocks used with the trailing/ leading forks bffer more sophisticated damping control than the universal damping rods used in conventional slider· type forks. Engine design is another place where major changes continue, too. This year, Team Suzuki has done away with case reed induction for the RN factory bikes, joining Yamaha, Kawasaki, Honda and Husqvama with cylinder reed valve induction designs as the best possible way to tractable and powerful powerbands for their monster engines. One area where engine design continues to differ for Open class bikes is the actual displacement being used. This season, variations have been tried by nearly every factory team in sizes from !l60cc to 49Occ. Many Smith favors Honda's !l6Occ engine, and Brad Lackey like Kawasaki's !l90cc mill. They feel a smaller motor is easier to control, offering faster lap times and less rider fatigue. The only problem comes when they have to race against bigger displacement bikes like the 450cc Honda of Graham Noyce or Heikki Mikkola's 454cc works Yamaha. The bigger bikes get the jump on the stans and down the straightaways, then block the smaller bikes in the turns or more difficult sections of the track where the smaller bikes are supposed to be at an advantage. Motocross bike design has come a long way in the last 10 years. With the increase in technical knowledge we now have, however, the next three to five years should be just as progrssive and a lot more exciting. Here's a quick look at the trick machinery that graced the track at Bel· Ray USGP of MotocJ"OS$. Suzuki RN~79: Rug. DeCoater got 23 more cc's to pley with this yeer Inside a new reed VlIIve Inducted cylinder. The Bruce Burnea-designed trailinglleedlng ex" front forks offer 290mm of travel and better damping control than Suzuki'. reguler Showe 280mm works forks. R. . suspenaion is provided by Ohlin. reservoir shocks, also, with 330mm travel. All the worka RN SuzukIs weighed In between 218-220 pound•.