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/126938
Chuck Gardner's Harley-Davidson XR750. which was campaigned by Steve Eklund this year. on Branch's dyno. at least two purposes: To decrease the cost of racing by reducing the rpm of the engines, and, with careful selection of restrictor sizes for the Harleys and Hondas, make the racing more even between the two brands. Even though Boyce denies the influence, it cannot be lost on him 3J!d his colleagues that Bubba Shobert, the most successful rider on the circuit, tegularly gets booed simply because he is riding a Honda and a majority of dirt track Doug Polen had a p.etty good day in Georgia. He came home from the 500 Interceptor'" Series Fmal at Road Atlanta with $5000 in prize money, a giant trophy and the title of Interceptor Series Champion To earn his victory, Polen had to fight off 24 of the fastest Interceptor'" racers in the country. Guys who had finished in the top five in their division during the year. Right off the line it was tough. li.l..-;~~......;i;;"..--";'~"""" A light rain had race fans are highly partisan Harley enthusiasts who see Honda's millions as unfair advantage. It doesn't mattet whether they are wrong or not, it only matters that they boo. Intake air flow restriction has a · rather benign effect on a highly tu~ engine, as was demonstrated when the AMA recently conducted tests at Jerry Branch's dyno facility in Cypress. Calirornia. Both 750cc twins and 600 singles were tested. The singles were included for two reasons: First, if the AMA does choose to restrict the 750s, they wouldn't want to reduce their power · so much that the singles would be competitive. They would need to know how much power a good 600 makes. The AMA feels that twins are · important to filling the stands and that making the singles competitive with them could be a disaster at the box office. Second, a suitable set of restrictors in a twin could make them equal to the singles and that, in turn, could allow a Junior rider to buy a $10,000 (or so) twin instead of a $6000 single now and a $10,000 twin next year after he gathers his Expert points. Both the Honda 600 and Wood· Rotax 600 produced about 60 horse· power. In the 750 class, two Hondas were tested; Hank Scott's remarkable 107 hp Honda and a stock 92 hp engine from Honda's own inventory. Two Harleys were there too: Chuck' Gardner's very good 92 hp XR and ScOtt Parker's 100 hp factory racer (the most powerful XR ever tested by Branch). After each engine's un·re· stricted power characteristics were reo corded by the Super· Flow computer· ized dyno, various sized restrictors (34 to 29 millimeters) were installed in the rubber adapters between the car· buretors and the intake manifolds and the tests were repeated. A considerable number of computer print· outs were thus generated documenting the actual effects of intake restrictions on each engine. Among the calculations automati· begun to fall, and Scott ~ Zampach jumped out to an early lead. fur 10 laps Polen chased Zampach. Then the rain stopped, the track began to dry, and Polen turned up the wick. Doug took the lead on lap 11 and set a winning pace from there on out Congratulations, Doug, Scott, and all the rest of you :whoeamed BONDA_ a total of $110,000 . . mpnzemoney during the year and made the 500 Interceptor Series a complete success. ';;51i1.irirJ"l\J;;iiiiiriiii~ Good riding, guys. t::HAMPtdvs,1::HlJjr::!nDfJ...s