Honda's 500 Gp V-Twin

HONDA'S 500 GP V-TWIN

HONDA WILL FIELD A PROTOtype 500cc V-Twin two-stroke in next year’s grand prix roadracing series, and a production version will be offered for sale in 1997.

The present 180-plus-horsepower four-cylinder bikes are stalled, generally unable to improve on laptimes from 1991-92 despite improvements in every area of design. Because 250s are continuing to go ever-faster, Honda has chosen to explore the special rules for Twins, which permit a 242pound minimum weight instead of the 286-pound minimum for Fours. The new machine will produce a realistic 135 horsepower, but hopes for the NSR500V aren’t based upon its power. Engineers note that 250 corner speeds are substantially faster than those of current 500s-about 6 mph faster in a 65-mph corner Honda presented as an example. Although 500s accelerate much faster than 250s, their slower corner speed requires them to accelerate from a lower speed, so they often take just as long to reach the next corner.

Could it be that the dirttrack style of steering GP bikes with rear wheelspin has reached its limit, and is about to be eclipsed by the 250 style of more equal use of front and rear traction?

Further information provided by Honda shows overall 250 performance getting steadily closer to that of 500s, year by year. In 11 out of 14 GPs in 1994, the top 250 laptime was within 2 percent of the top 500 time. This suggests that a machine with 250-like weight and handling, but with one-third more power, might be a potent combination. This kind of thinking was the basis for Honda’s first two-stroke GP bike, the NS3 of 1982, and has been tested in a limited way by Aprilia recently, with a 400 cc version of its title-winning 250. However, because all but one of the NS3’s wins were delivered by Freddie Spencer, the question of who deserves the credit-man or machine-is unclear. The Aprilia 400 has been plagued by piston and other troubles, and also has yet to find its Spencer. Honda officials note that there is value in building “machines with extreme directions,” and many of theirs have been successful. The new NSR500V will be a fascinating experiment.

Kevin Cameron