Fly By Wire

fly by Wire

Yoshimura Suzuki GSX-R 1000

MATTHEW MILES

AIN’T NOTHIN' WRONG WITH SUZUKI’S GSX-RIOOO. HAMAMATSU’S OPEN-CLASS repli-racer cranks out a whopping 144 horsepower at its 190mm-wide rear Dunlop, tips the scales at a scant 407 pounds and tops out at a faceshield-flattening 175 mph. “Unless you’re a highly skilled operator,” we advised in last April’s “Family Feud” Gixxer roundup, “the 1000 is just too much motorcycle.”

Well, Yoshimura doesn’t quite see it that way. The longtime purveyor of go-fast bike bits has a long history of hot-rodding Suzukis, many of them GSX-Rs. We’ve sampled our share of ’em, too, from the 1340cc “Big Papa” repli-racer to Mat Mladin’s championshipwinning Superbike.

But both of those bikes, and nearly all of the others, were carbureted. Fuel-injection being the wave of the future-heck, the future is now!-meant the old dogs at Yosh had to learn some new tricks. Or hire someone schooled in circuit boards and serial cables.

Which explains why Cal Poly Pomona graduate Brett Miller smells like a dyno room. The 27-year-old ex-amateur car racer has played an instrumental role in the development of Yosh’s new Engine Management System. The Dynojet Power Commander-like device mounts inside the GSX-R’s tailsection (and those of other Suzukis and various Aprilias, Hondas, Kawasakis and Yamahas) and plugs neatly into the bike’s stock wiring harness. No splicing or other modifications required.

The compact $475 unit comes pre-programmed for use with a Yosh exhaust. Other maps may be downloaded from Yosh’s website (-www.yoshimura-rd.com), or users can plot their own application-specific fuel and timing maps using any PC. Further upping the ante, the Accessory Hub Kit ($475) includes a handlebar-mounted switch that allows the rider to toggle between as many as three pre-set maps while on the fly. How cool is that?

The accessory kit also includes an rpm-selectable tachometer-mounted shift light and a clutchless shifter/gear-position offset. Because the GSX-R is equipped from the factory with a gear-position sensor, the fuel and timing maps can be “trimmed” for each ratio. The “kill time” between full-throttle, clutchless upshifts can also be tweaked, just like on Mladin’s Superbike. The final addition is a remote serial port for quick lap-top access. Installation of the basic unit takes about 35 minutes; figure on 3 to 4 hours for the complete setup.

This is Yosh’s first crack at the big Gixxer, which is why it doesn’t glitter with every conceivable component from the company’s 120-page catalog. Bore and stroke are stock, but Stage 1 cams ($700), headwork ($775), a compression-upping thinner head gasket ($160), kit ECU ($550), BMC air filter ($75) and a titanium Duplex exhaust with midrange-enhancing crossover tubes ($1590), combined with the aforementioned EMS mapping, deliver a 14-horse boost in peak power. Yosh also yanked the counterbalancer and radiator fan, and installed a lightweight racing generator ($315).

Aside from a lumpier idle, slightly quicker spin-up, a few more tingles through the bars and a deep, growly exhaust note, the modified motor behaves pretty much like a stocker-until the tach needle crests 6000 rpm, that is. At that point, all hell breaks loose. Assistant Editor Mark Cernicky returned from the wheelie-packed photo shoot with a larger-than-usual grin on his face. “Usually, I can guess my speed within 1 mph,” he enthused, “but on this thing, my internal clock is off by at least 10 mph. It’s so fast! It really belongs on a racetrack.” That said, it’s pretty difficult to discern any seat-of-thepants differences between the “optimum,” 5 percent leaner or 5 percent richer maps with which the Yosh GSX-R was equipped. Mladin himself rode the bike during a recent test at California Speedway’s new road course. After a handful of laps, he pitted and proclaimed, “The third map works bitchin’!” Then again, he’s Mat Mladin.

The chassis is largely stock, with changes limited to rearsets ($575), nylon frame protectors ($65), steel-braided brake lines, race-issue Tokico brake pads salvaged from Yosh’s pre-Brembo days and fresh Dunlop rubber. The Supersportspec D207 GP Stars have very triangular profiles and the rear is 10mm narrower than stock, the sum of which makes directional changes an afterthought. In fact, the Yosh GSX-R responds to inputs as if the steering damper had its insides hogged-out (it didn’t). The only downside is that the front tire tends to follow rain grooves and pavement imperfections.

But, boy, does it know how to find an apex!

Of course, the real news here is the EMS package and what it represents for creatively minded sportbike riders. For example, one Yosh customer with whom map-whiz Miller has worked closely was looking to outfit his Kawasaki ZX-12R with a nitrous-oxide system, but wanted to keep the bike’s appearance stock. So, he installed an EMS and accessory pack, then converted his ZX’s horn button to trigger a nitrousspecific map that not only added the juice, but dumped in more fuel and retarded the timing, too.

The possibilities are endless.