At Last! Bimota's Two-Stroke Hits the Street

AT LAST! BIMOTA'S TWO-STROKE HITS THE STREET

ROUNDUP

NEW FOR '98

RADICAL, INNOVATIVE, Futuristic, avant-garde-all those absolutes apply to the Bimota 500 Vdue. After a long, drawn-out development cycle lasting the better part of this decade, the world’s first clean-burning two-stroke sportbike finally is entering production.

Barring any more last-minute delays with suppliers-principally Morini, the Bologna-based builder to which Bimota has subcontracted manufacture of the Vdue’s engine-the many customers who plonked down deposits months ago (years, even) to be first in line will be able to get their hands on what promises to be the benchmark machine.

Bimota has taken this next great leap forward by finding a way to enjoy the benefits of twostroke engine technology (primarily a better power-to-weight ratio than a comparable fourstroke) while overcoming the inherent drawbacks (excessive hydrocarbon emissions). It’s a mark of the genius and determination of Bimota’s small R&D team, led by Pierluigi Marconi, that they’ve been able to create a motorcycle clean and quiet enough to meet the stringent standards of California and Switzerland, while delivering a level of performance so far seen only on the racetrack.

Marconi recalls the genesis of the project: “After almost two decades of using other manufacturers’ engines to build our bikes, we wanted to produce the first 100 percent, Bimota-engined Bimota. But the capital investment needed to develop our own four-stroke engine could only be repaid with much higher production volume than Bimota ever could consider, so it had to be a two-stroke. That, in turn, meant we had to develop our own fuelinjection system, because emissions are a critical factor for two-stroke engines. Finally, the 500cc capacity then chose itself, because Bimota’s policy always has been to participate in competition as a means of developing new models. The FIM’s new (lower) twin-cylinder weight limit for the 500cc GP class meant this project was born from that policy-and indeed the idea of going GP racing in the future has not been discarded.”

But the GP circuit may not be the only venue in which the Vdue will compete, as Marconi suggests. “We haven’t yet asked the FIM to allow 500cc twin-cylinder two-strokes into Superbike racing, but I do believe this is something they must consider. There’s no doubt motorcycles like the Vdue will add a fascinating extra dimension to Superbike racing, perhaps resulting in the long-awaited merger between Superbike and grand prix classes.” The Vdue’s engine is a liquidcooled, crankcase-reed-valve-inducted, 499cc, 90-degree V-Twin, with twin counter-rotating crankshafts to eliminate primary vibration. Its 72.0 x 61.25mm cylinder dimensions are more oversquare than the Flonda NSR500V racer’s 68.0 x 68.5mm measurements, a decision Marconi explains with one word: “Revs! In racing form, our engine makes 135 bhp at 11,200 rpm at the back wheel. But I believe that in 500cc GP racing, it’s important to have a Twin revving to at least 11,500; our engine is a happy compromise between the Honda, which only revs to 10,500, and the (400cc) Aprilia, which turns to 12,000, but which suffers from the handicap of not being a full-size 500.”

So how does the Vdue work? After riding a pre-production bike at the Monza GP circuit and in the surrounding countryside, I honestly can say that Bimota has reinvented the sport motorcycle.

To start with, the Vdue sounds nothing like a traditional twostroke; there’s a basso profundo crack to the exhaust note that sounds incredibly muscular -sort of like a two-stroke desmo V-Twin, if you can imagine that contradiction. The only unpleasant noise is a shrill rattle from the dry clutch, which has been the biggest hold-up in getting past noise tests.

The engine is incredibly wellbehaved and tractable down low, pulling from less than 2000 rpm at part-throttle. More surprisingly, it does so without having to use great fistfuls of clutch. And there’s surprisingly little vibration, even at high revs.

Above 7000 rpm, acceleration is awesome: Nothing else with a license plate prepares you for the rush of performance that the Vdue delivers up high. And it’s fast: I repeatedly saw 150 mph on the Monza pit straight.

Given its powerful (105 bhp at 9300 rpm at the rear wheel) engine, light (319 pounds dry) weight and short (52.8-inch) wheelbase, you’d expect the Bimota to be a wheelie-hound, but this is not the case. It’s also not at all cramped, even for a 6footer like myself.

The Vdue is not, however, perfect: Bimota still has some work to do on the engine, which has a curious occasional hiccup around 9000 rpm, and an irritating reluctance to accelerate cleanly wide-open after changing into fifth or sixth gear at 9500 rpm. Furthermore, the engine runs roughly and the transmission snatches horrifically if you try to maintain constant throttle while riding slowly in traffic. Throttle action also is Stifter than you might expect from a fuel-injected motorcycle, gear changes are high-effort and neutral is nearly impossible to select at a standstill. The bike I rode was, however, a prototype, and Marconi says these few flaws will be addressed on the production models.

With the Vdue, Bimota has given us the first of what will surely be a new generation of ’stroker sportbikes. Even if you can’t afford the $20,275 purchase price, you’ll have cause to be grateful to Bimota in coming years, because it’s a safe bet that the Japanese are waiting to see how the Vdue fares before launching similar products of their own. A page truly has been turned-but how ironic it is that a chassis specialist is showing engine manufacturers the way ahead. -Alan Cathcart