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/126413
Super Trick Machi ery By Jim Gianatsis hey are the most technically advanced dirt bikes ' in the world. Plastic. , hardened to weight T titaniumtipaluminum and amagnesium rocketships A hot millionT-6 andworth of measured to the scales like helium filled balloon. bucks factory works machines will be crouched behind the starting gate for the third annual Mr. PiBB sponsored New Orleans Superdome AMA/Toyota Supercross on June 2, ready to pounce out on the masticatory man-made indoor dirt battlefield for the locking of horns in the most exciting clash the city has seen since General AndrewJackson ran the Red Coats down river in 1814 . Yamaha OW-40 Team Yamaha rider Mike Bell and mechanic Dave Osterman exhibit the winningest and most highly-refined motocross bike in the history of the sport. The Monocross rear suspension system was introduced by Yamaha in 1973 and has seen continuous development since to become possibly the most reliable and best performing bike around . Innovations like a deCarbon shock, chrome plated cylinder. reed valve induction, COl ignition , monocoque frame, watercooling. and now double leading shoe front brakes were b all first tried by Yamaha for motorcross and proven . successful. This 250cc Supercross bike. identical to that of teammate and series points leader Bob Hannah , has 11.5 inches of suspension at each end provided by Kayaba air/spring front forks and a Yamaha reservoir monoshock, It is the only bike of all the factory machines that in its ready-to -race form has to have extra weight added to it in the form of steel axles and bolts. replacing the usual titanium. to meet the FIM minimum weight limit for the class at 196 pounds. Each factory machine is new from the ground up . Each sports new chassis and engine designs different from what were tried at earlier Supercross races this year. The short lO-inch suspensions which many of the teams experimented with at the first few races didn't work out too well when the tracks broke down and got rougher than hell . A slight advantage in cornering stability for the shorter travel bikes just wasn't worth the price. All the teams are now back to 12 inches of suspension so their throttle-pegged jockeys can damn the bumps and power themselves wide open around the most treacherous and demanding stadium course east of the Los Angeles Coliseum. Here is your preview of the weapons for Superdome Saturday night. Kawasaki KX-250 SR Jimmy Weinert claims the works Un i-Trak Kawasaki will be available for sale as a production bike next season. The Uni-Trak rear suspension . which positions the single Kayaba deCarbon reservoir co il-over rear shock inside the swingarm just behind the engine where it operates on the swingarm by way of levers and a rocker arm . was first used successfully a couple of years ago on road race bikes . The Uni -Traks are being used by Team Kawasaki in all three displacement classes and are proving them- selves to be highly compennve for a first -time effort. In Europe. Kawasaki factory rider Brad Lackey is presently leading the 500cc World Championships with his 420cc Uni -Trak and may possibl y become the first American to ever win a world motocross title. The bikes are about 10 pounds heavier compared to the works Yamahas, but Kawasaki will correct that problem with forthcoming magnesium engines to replace the aluminim productionbased 5-speed engines with reed valve cylinder induction and Electro-Fusion iron plated cylinders now used . )/ er 'T eam Suzuki entered the 1979 season at the Hangtown Nationals ith a proven design that actually has a lot of major detail refinements . mong them is a new frame for the 50cc and 420cc works bikes which is ighter and simpler in construction han what was used previously . aking the ' bike a departure from hat had been the closely rela ted RM roduction machines. Engine cases are Iso redesigned to allow for a larger ase reed induction system. The dual ase reed and cylinder reed induction ystem first tested by Roger DeCoster n the Trans-AMA Series last fall is still being used by him in this year's 500cc World Championship events. but has yet to find I'ts way to the RH 250 factory bikes . Kent Howerton's works racer is only slighty " hea vy" at 205.-210 pounds . Suspension is provid ed by Kayaba with special works air/spring forks giving 11 inches of travel at the front and deCarbon reservoirshocks canti levered to dish out 12 inches of travel in the rear. Such goals are easily within reach of a privateer rider modifying his RM -250N with quality after -market suspension pieces . Later in the year we may get to see the radical new leadingltrailing link front suspension system being used by DeCoster in Europe. Honda RC-250-79 Three different works RC bikes are being used by Team Honda for the 250cc outdoor Nationals and the Supercross Series . The first is the fairly conventional . single front downtube RC, nearly identical - with exception to the quality of suspension com ponents - to the present production CR-250R. This is the bi ke favored by Marty Smith and Gary Sernics, and once again a privateer can duplicate this bike by adding better quality suspension components to his own bike . Next isthe new twin downtube frame AIDD bike with center port ex haust cylinder. Advantages of this Type III design over the proven Type Il a re reported to be a slightly more rigid frame and 1-2 more horsepower from t he engine. This is the bike Marty Tripes likes. and is expected to be the prototype for the 1980 production CR since many of the present production pa rts. with the exception of the frame and cylinder. will remain the same. Steve Wise is riding the most exotic of the RC-250 works bikes. shown here with tuner Cliff White. This bike utilizes the new twin down , tube frame along with a completely new long stroke , centerport engine. If Honda ever wanted to sell an Open class production bike, th is engine could probably be the basis for a common 250/400cc powerp,lant. 19