2010 Aprilia RSV4 Factory - The "Other" Italian Superbike

Better or just different?

By Brian Catterson, Photography by Aprilia, Milagro

Hard Parts
Are double the cylinders twice as good?

Aprilia was first to employ a fly-by-wire throttle on its ill-fated Cube MotoGP triple, and now joins Yamaha in offering the system to the public. As on the R1 and R6, the RSV4's twistgrip pulls a cable that's linked to an electronic solenoid, which in turn opens the butterflies in the quartet of 48mm throttle bodies. Three selectable modes let the rider tailor throttle response to suit conditions: "Track" mode is full-power; "Sport" cuts torque by 25 percent in first through third gear; and "Road" reduces power 25 percent across the board, peaking at 140 bhp. The Weber-Marelli EFI employs two injectors per cylinder--a conventional one inside the throttle body and another showerhead-type injector high up in the airbox, switching from the former to the latter between 6000 and 7000 rpm. Also like the R1/R6, the RSV4 employs variable-length velocity stacks (on the Factory, but not the base model), a stepper-motor-activated worm gear switching from torque-producing 265mm-long funnels to power-producing 230mm shorter funnels at 10,000 rpm. The Magnetti-Marelli ignition features one spark plug per cylinder with stick-type coils. The ECU also controls a butterfly valve in the Euro 3-compliant 4-2-1 exhaust, the valve opening fully at 6500 rpm. Traction control isn't offered, but is being used on the factory World Superbikes so should be available as part of the inevitable race kit.

Unlike most other Italian sportbikes, the RSV4's pressed-aluminum and cast-sheet twin-spar frame is not a thing of beauty. Purposeful-looking is more like it. It is light though--claimed weight is just over 22 pounds. The swingarm is said to weigh half that much and is asymmetrical to clear the pentagonal-shaped muffler on the right side. According to the press materials, the chassis has "envisaged" adjustments for headstock position, rake, engine and swingarm-pivot height--realized with the aid of race-kit parts, of course. The plastic gas tank sits behind the airbox and extends down below the rider's saddle for optimum weight distribution. Suspension consists of a 43mm hlins inverted fork with TiN-coated stanchions and high/low-speed compression damping, while the hlins shock has but a single compression knob. There's also an hlins adjustable steering damper. (The base model will get downgraded suspension, and likely a fixed steering damper.) Front brakes are the latest radial-mount Brembo Monoblocs with four 34mm pistons each, activated by a radial master cylinder and braided-steel lines. The rear brake uses a two-piston Brembo caliper, actuated by a tiny master cylinder with an integral reservoir as on current dirtbikes. Forged and machined, aluminum-alloy, 10-spoke wheels hold Pirelli Diablo Supercorsa SP (for Sport Production) tires--essentially a more durable version of the World Supersport-spec Supercorsa SC (Special Compound).

Forget everything you know about the Rotax-built V-twin employed in previous Aprilia sportbikes, this V-4 is all-new. The 65-degree angle between cylinders is wider than the 60 degrees of previous Aprilias, but narrower than the 90 degrees of Ducati V-twins and the Desmosedici RR V-4, or the Honda V-4 Interceptor. While Aprilia engineers admit this engine configuration isn't optimal for peak power--that distinction goes to an inline-four--they claim it is optimal for handling, as evidenced by its use in the Ducati, Honda and Suzuki MotoGP racers. With a single gear-driven counterbalancer in front of the cylinders, the "V" configuration is also smoother than an inline and gives the engine a natural, offbeat, "big-bang" firing order that improves traction. And it allows extremely oversquare cylinder dimensions (78 x 52.3mm--within a decimal point of an '09 Yamaha YZF-R1), which equate to 999.6cc--just shy of the World Superbike displacement limit. Those bores hold forged 13:1 compression pistons, topped by 32mm titanium intake and 28mm Nimonic steel exhaust valves, each with nested springs, set at a very flat 22-degree included angle. Dual chains spin the intake cams, which spin the exhaust cams via idler gears. Valves are opened directly via shim-under-bucket actuation. The wet-sump lubrication system features dual oil pumps housed in a magnesium sump, with temperatures held in check by an oil cooler that complements the coolant radiator. A cassette-style gearbox allows quick ratio changes for racing, while a mechanical slipper clutch replaces the old vacuum-operated diaphragm setup. Claimed output is 177.5 horsepower at 12,500 rpm and 84.8 lb.-ft. of torque at 10,000 rpm.

The RSV4 was designed to be as compact as possible, with the silhouette of a 250cc Grand Prix racer. Really it's closer to the size of a 600, but happily accommodates taller riders. Though sketched by a Spaniard, it's obviously Italian. The sexy look starts at the front with a three-headlight array, and culminates in the rear with the pointy tail, which looks like a Latin take on the Honda RC212V MotoGP racer. Both the nose and tail are finned, and unlike any other sportbike. The bodywork was said to be tested extensively in Piaggio's own wind tunnel to ensure that it's as aerodynamically efficient as possible.

By Brian Catterson
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