Bimota Yb9sr

Bimota YB9SR

BUILDING A BETTER YZF600R?

AT THE MILAN SHOW LAST OCTOBER, THE BIMOTA display held a variety of Ducatiand Suzuki-powered gems that got lots of attention. Lost in the showtime, showbiz swirl was a model that deserved equal scrutiny. It's the YB9SR, a new 600-class sportbike powered by Yamaha's YZF600 engine.

This isn’t the first YB9, mind you. This bike’s predecessor, called the Bellaria, was. It used the old FZR600 engine and had odd, two-seater styling. In spite of some race wins in the hands of Bimota test rider Gianluca Galasso, it was not a particularly successful design, having been drawn more to satisfy company brass than the curiosity and creativity of its designer.

So now we have this new design, which is not destined for the U.S. It’s likely to find some eager customers in Europe, however, for it is a true hard-nosed supersport contender, with unashamed racetrack breeding, a nominal passenger seat and aggressive styling based on that of Bimota’s Tesi ES. Bimota has hit the supersport target spot-on, the second time around.

This is a completely new bike that shares only the overall design of the previous YB9’s twin-spar frame, and even that’s been modified, its head angle steepened from 24 degrees to 23.5. Everything else is new.

That certainly applies to the bike’s YZF600 engine. It’s unheard of for any manufacturer to deliver to an outside company supplies of its latest engines before the model it’s derived from is in production. But that’s what’s happened here. Though Bimota left the engine completely standard, the YB9SR has 4 more horsepower at the top end than the engine does in the YZF chassis, delivering a claimed 104 at 1 1,750 rpm at the crankshaft. This improvement comes thanks to the freer-flowing 4-into-l Bimota exhaust that replaces Yamaha’s 4-into-2-into-1 system, and to a revised airbox design.

Throttle response on the YB9SR is so vivid you run the risk of unhooking the back tire momentarily when cranked over on bumpy surfaces, even if you twist the wrist with care. But the crisp acceleration you get from as low as 3000 rpm—the big hit of power happens at about 8000 rpm-is ample payoff for this rather sudden throttle response.

Designer Pierluigi Marconi says his main objective in adapting the old YB9 frame to this new model was to change the bike’s steering geometry and weight bias to make the bike steer quicker and to improve front-wheel grip. As part of a formula designed to achieve those goals, he raised the rear-suspension ride height considerably, and got what he sought: a 52/48 percent front-wheel weight bias on a wheelbase of 53.9 inches. This base chassis beneFits from a Paioli shock that offers very progressive action and is surprisingly supple for such a dedicated sportbike. The 41mm Paioli fork is the same conventional unit Fitted to the DB2, and is fully adjustable. The front wheel did chatter over ripples in the road when the bike was laid over—possibly not enough rebound damping, or perhaps the weather was too cold for the high-viscosity oil in the fork. Front brakes are composed of a pair of 12.6-inch rotors and Brembo calipers, and in keeping with the bike’s sporting theme, they supply all the stopping power you’ll ever want.

The YB9SR is what the Italians tenn molto impegnativo, meaning that in spite of its small stature, this is a physical bike to ride, and ultimately quite tiring. The reason is that you’re sitting far forward, with a lot of your body weight on your arms and shoulders over low-mounted clip-ons, all in a conscious effort to help load the front wheel. This GP-style riding position is very effective, though it makes the bike feel more like a 250 two-stroke than a four-cylinder 600.

In spite of sacriFicing comfort for handling, there were times when for no apparent reason the bike suddenly seemed to knife into a turn, rather than laying in controllably and accurately. This trait was more disconcerting than dangerous, and never had the front wheel actually tucking under.

But this sudden transformation from slight lean to full lean happened much more quickly than I’d intended. Marconi attributed this to the 120/60 front Michelin Fitted to the bike, which he says Bimota will homologate as an option so customers can use it for racing, where it gives much faster steering than the 120/70 the streetbike will be sold with. This higher-aspect tire apparently has more neutral, if less precise, steering with a softer feel, because of the greater inbuilt flexibility of the tire sidewall compared to that of the lower-profile tire.

It’s amazing how much Bimota has accomplished in the little more than four months of the YB9’s development life. Make no mistake, this is a capable motorcycle offering a very high level of specification for the class. Only the last bit of refinement is needed. The essentials already are there.

So in Europe, at least, it looks like the 600 supersport category is about to have a new class standard imposed on it, and at the realistic price-in Europe, at least-of about $15,000. American 600cc fans with a taste for the exotic and access to the gray-market pipeline are advised to make the most of it. Alan Cathcart