A Step Closer To Gp Reality For Bimota

A step closer to GP reality for Bimota

ROUNDUP

BIMOTA, THAT TINY ITALIAN SPEcialty firm noted for building high-quality racebikes that spawn high-quality streetbikes, has turned an important corner. It recently completed the very first test outing of its all-new two-stroke 500cc GP bike, the Tesi 500.

Reviews of that outing, however, are mixed. On the plus side of the balance sheet is that the bike’s engine, a fuel-injected 90-degree V-Twin, purpose-built by Bimota, looks very promising. On the negative side is that the bike’s radical Tesi chassis still needs a great deal of development.

Testing was done, with Italian Superbike pilot Francesco Monaco at the controls, late last year at the Misano Adriático track on a day that featured heavy rain and very cold temperatures. With the track wet and slippery, there was very little opportunity to use the full potential of the bike’s engine, said to develop 119 rear-wheel horsepower at 9800 rpm. That’s a long way from the 170 horsepower being developed by the Fours now raced on the GP circuit, but there are three reasons for optimism.

The first is that the engine ran reliably all day long. The second is that this engine can be safely revved past 11,000 rpm, and where there’s additional engine speed, there’s additional power. The third is the excellent spread of torque expected from this V-Twin, a spread Bimota designer Pier-Luigi Martini says will be wider than that developed by the V-Fours it will compete against.

This engine is mounted in usual GP fashion, with its forward cylinder pointed toward four o’clock,

when viewed from the right side of the chassis, and its rearward cylinder pointing upwards toward one o’clock. It is fed by a quartet of fuel injectors that empty their charges into a single 65mm throttle body, and is cooled by a pair of aluminum radiators, rather than the more usual single curved unit.

If there was some reason for optimism with respect to the engine, things concerning the bike’s chassis are not quite so bright. The bike, with its hub-center front suspension, tipped the scales with a dry weight of 281 pounds-5 pounds under the minimum required for Fours, but way above the 209-pound minimum allowed for Twins. On the bright side is the fact that this bike is the first rolling prototype assembled for initial testing, not a refined, race-ready unit. As such, all its chassis parts were aluminum instead of lighter materials, with no carbon-fiber used anywhere. Use of lighter chassis parts and carbon-fiber bodywork apparently will have to wait for subsequent members of the Tesi 500 family.

So, mixed reviews. The engine works well, and there’s the promise of more power to come. But the chassis badly needs to lose weight. Will the necessary work be done in time for the Japanese GP, now tentatively set for February 29? Indeed, will it be done in time for the bike to run in any of this year’s GP races? Only time will tell. But at least Bimota’s GP bike has turned its first comer. It exists, it runs and it shows promise. —Bruno de Prato