2010 Aprilia RSV4 Factory

[iqurean]

Despite the current economic implosion, these are very good times to be sportbike riders. In the space of three months, we've been presented with two radically different alternatives to the sportbike status quo. First came the MotoGP-inspired crossplane-crank Yamaha R1. Now, hot in its tire tracks, comes the totally unique Aprilia RSV4, as fine a piece of clean sheet engineering as we've seen yet in the literbike class, with its ultra-compact 65-degree V4 powerplant. The fact that these two bikes proved so effective straight out of the box at the highest level, flanking the reigning world champion Ducati desmo V-twin—a third different option in superbike engineering—on the Qatar rostrum in the second race of the '09 World Superbike season, shows that each company did its sums right.

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The chance to join journalists from all over the world at the Misano GP circuit in Italy to ride the production Aprilia RSV4 at the world press launch was initially subdued by the fact that it rained all day. Even in the dry, this is one of the MotoGP calendar's least-grippy tracks, and it becomes a skating rink in the wet. But close study of the weather forecast revealed that—just maybe—it'd be dry and bright the next day, and it was. Convincing Aprilia to let me have another go, this time in Italian spring sunshine, was the work of a moment. But at least this way I got to ride the Aprilia the way it was meant to be ridden, on a dry track.

But the most impressive aspect of the RSV4 is the performance of that wonderful engine offering the best of both worlds between a four and a twin. To design the new motor, Aprilia hired one of Italy's greatest living engine progettisti, Ing. Claudio Lombardi, 67, creator of the fabulous Lancia Delta Integrale racecar that won four World Rally titles between 1987 and 1992, before he moved to Ferrari. After a stint as its Formula 1 race team manager, he then served as Technical Director until ‘94, where he moved to Ferrari's GT and sports car engine department, becoming responsible for creating the V8 engines powering many Ferrari automobiles today. The RSV4 is his first motorcycle engine design, created entirely in Aprilia's Noale base where he works full time.

The result of Lombardi's efforts is a unique 65-degree V4 engine, with horizontally-split crankcases and the Nikasil cylinders cast integrally with the upper crankcase half for greater stiffness. "When we started work on the project in September 2005, the intention was to design a 60-degree V4," says Lombardi. "But it soon became clear that the intake tract was flawed. By opening the cylinder angle out slightly to 65 degrees, we had the straighter run that was needed to obtain our design target of 180 horsepower in street form." A single gear-driven counterbalancer in front of the cylinders consumes an estimated three horsepower in canceling out the vibration caused by the narrow cylinder angle. "It's slightly better balanced now than a 90-degree V4 engine," declares Lombardi with satisfaction, although he admits, "I don't pretend it's ideal, but it isn't an unduly tall engine package, either," referring to the fact that the bank of four 48mm Dell'Orto throttle bodies can't be sunk any lower between the cylinders owing to the narrow angle. "It's perfectly satisfactory in terms of height, and allows us to produce the narrow, compact motorcycle we were seeking."

Despite the 999.6cc engine's seemingly radical oversquare 78 x 52.3mm bore/stroke dimensions, Lombardi says he'd have preferred an even shorter stroke, but was forced to settle on this configuration by the World Superbike rules then in effect. "At the time we were designing the engine, the FIM had imposed a 1.5:1 bore-to-stroke limitation on four-cylinder machines, to protect the 1000cc twins," he says. "By the time this restriction was removed from the SBK rulebook for ‘08, to allow 1200cc twins, it was too late for us to change. I would have preferred to have a shorter stroke, for more power at higher revs, while still retaining valve springs. I had experience at Ferrari with high-revving non-pneumatic valve engines, and it would have been good to adapt this technology to the RSV4."

2010 Aprilia Rsv4 Factory
MSRP: Approx. $26,000
Engine
Type: Liquid-cooled, four-stroke DOHC 65-degree V-four
Displacement: 999.6cc
Bore x stroke: 78.0 x 52.3mm
Compression ratio: 13:1
Induction: Weber Marelli EFI, 48mm throttle bodies w/variable length intake, two injectors/cyl.

Chassis
Front tire: 120/70ZR-17 Pirelli Diablo Supercorsa SP
Rear tire: 190/55ZR-17 Pirelli Diablo Supercorsa SP
Rake/trail: 24.5 deg./4.1 in. (105mm)
Wheelbase: 55.9 inches (1420mm)
Seat height: 33.3 inches (845mm)
Fuel capacity: 4.5 gal. (17L)
Claimed dry weight: 394.6 lb. (179kg)