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Yoshimura Dials in the GSX-R600

Everyone who knows anything about motorcycle roadracing, whether in the United States or abroad, knows the close ties between Yoshimura R&D and Suzuki. The Yoshimura-backed Suzuki team has taken Australian Mat Mladin to two consecutive AMA Superbike championships, and Yoshimura is also responsible for dialing in, and racing, the factory Suzuki 600 supersport bikes here in America.

In connection with our evaluation of the new GSX-R600, Brad Stevens of Yoshimura R&D of America was kind enough to share a dyno chart with us — showing horsepower numbers for a stock 2001 Suzuki GSX-R600, as well as the same bike fitted with Yoshimura’s newly-developed full exhaust system (the same pipe that will be used by its supersport riders Aaron Yates and Jamie Hacking next year in AMA 600 supersport competition).

The stock numbers reflect numbers we had been hearing elsewhere, with a peak of 103.6 horsepower. The bike with a pipe only, and some minor fuel injection adjustments resulting in a richer air/fuel mixture (Brad indicates more thorough fuel injection re-map and ignition timing adjustments will be available early next year using Dyno Jet’s Power Commander product), provides 107.5 peak horsepower , with gains available everywhere above 5,000 rpm. Take a look at the dyno chart (in PDF format — you’ll need an Acrobat Reader program installed on your computer). The modified graph is even smoother than the stock graph.

Yoshimura sells their products through local dealers, but also sells direct. Yoshimura’s address and phone number is as follows: 4555 Carter Court, Chino, CA 91710; (909) 628-4722.

The Power Commander product will allow fine tuning of fuel injection mapping as well as ignition timing, and should provide even slightly improved results.

Privateer racers are looking for a cheap horsepower advantage. The 600 supersport class in local and regional race series is hotly contested. Obtaining more than 101 or 102 horsepower at the rear wheel is extremely expensive for a privateer running most of the current 600cc sportbikes, but not for the new GSX-R600. Suzuki may end up dominating the grid at 600 supersport events across the country, unless Honda’s new 600F4i provides similar horsepower figures.

By the way, word is Suzuki’s Aaron Yates was just as fast on the undeveloped 2001 model as he was on last year’s dialed-in supersport bike at a recent Daytona test.