Aprilia RS 250

The stopwatch never lies. As I flash across the start-finish line, flat-out in fourth gear, I press the button on the left handlebar and glance down. In a box alongside the tachometer, a digital display shows my lap-time: 2 minutes 0.48 seconds. Terrible! My previous few times have been under two minutes, but this lap I got a couple of bends all wrong and when you do that on the Aprilia RS250, the evidence is plain to see.

At least there was no team-manager frowning from the Misano pit-lane wall. This was not a factory team test session but the launch of Aprilia's long-awaited race-replica complete, like the real thing, with high-revving 250cc V-twin motor, chunky alloy frame and even a GP-style cockpit mounted lap timer. The Italian firm claims this bike is the closest you can get to a grand prix racer for the road, and in many respects it's hard to disagree.

There is certainly no mistaking the inspiration for the RS, even if this bike's colour scheme is the orange, silver and blue of Loris Reggiani's RSV400 rather than the black of Max Biaggi's championship-winning, Chesterfield-backed 250. The roadster looks lean and classy from its twin-headlamp nose section, through the elegant twists of the twin-beam frame and swing-arm to its racily angled rear end, which looks as though it's a self-supporting carbon-fibre structure.

In fact the seat unit is made from plastic and is supported by a conventional subframe, and the twin silencers are carbon-wrapped aluminium rather than the real thing. The bike's graphics are simple stickers, too, with no protective coating, which seems a bit cheap. But the finish and detailing is otherwise good, from the lap-timer which can record and store details of up to ten laps, plus give information on water temperature, battery condition and time of day to the seat hump, the top of which can be replaced with a pillion pad.

The engine is stamped with Aprilia's logo although the basis of the powerplant is the 90-degree V-twin from the RGV250. Suzuki's little two-stroke unit has been around since 1989, and has changed little in recent years. But close collaboration between the two factories has resulted in a number of Aprilia-inspired technical developments being incorporated into motors that are built by Suzuki, then shipped to Italy to be bolted into the RS.

New parts include the cylinder heads, which have a revised combustion chamber shape, plus larger-diameter coolant passages for improved temperature control. Cylinder barrels remain standard, although Aprilia insists on stricter tolerances. The bottom-end is essentially unchanged, but the clutch casing diameter is slightly larger, to improve oil circulation, and the flywheel cover is plastic instead of metal to save weight.

Elsewhere the ignition system is altered slightly, and the electronic control unit for the 34mm Mikuni carbs has three solenoids instead of two, which Aprilia says improves response. The airbox is new, and the biggest single change is the larger-volume exhaust system. According to Stefano Sartorello, the engineer in charge of RS engine development, the exhaust accounts for 90 per cent of the performance improvement.

Aprilia claims a peak output of 70bhp at 11,500rpm, and says the RS motor is about 9bhp stronger around 9000rpm and 5bhp more powerful at the top-end than the Suzuki original. (Aprilia refers to nine grand as the 'midrange', which says plenty about this engine's power characteristics.) The gain allows the RS to be geared slightly taller than the RGV, with one tooth fewer on the rear sprocket.

The compact powerplant is almost lost within the massive embrace of the frame, whose elegantly curved main spars are made from an alloy of aluminium and magnesium. Basic frame layout echoes that of Biaggi's racebike, though the RS uses cast, rather than billet, alloy at the steering head and swing-arm pivots. The roadster's steering geometry is considerably less radical, too, with rake and trail of 25.5 degrees and 102mm.

Front forks are 40mm upside-down units, made by Marzocchi to Aprilia's specification. The front end is adjustable for preload, via a screw on the top of the left leg, and for rebound damping via a knob on the right leg. Rear suspension is by a multi-adjustable Boge shock. Wheels are 17 inches in diameter at both ends, the front holding a typical big-bike braking combination of 298mm discs and four-piston Brembo calipers.

For a mere 250 that weighs just 141kg dry (2kg more than the RGV) the RS is physically quite large, too, as anyone who has ridden Aprilia's 125cc race-replicas might expect. Its riding position is similarly aggressive, with a fair reach forward from the low seat to the clip-ons. Unlike the 125s this bike has no electric starter, but the RS takes only a light kick before coming to life with a familiar RGV-like rattle.

Accelerating down the Misano pit lane for the first time, the RS matched the RGV with its lazy behaviour at low revs. Carburation was clean virtually all through the rev range, but there was very little power to speak of below 8000rpm. Coming on to the back straight at about 75mph, I put the bike into top gear, wound the throttle open at 7000rpm and by the end of the straight the RS had barely increased its speed at all. This is certainly no bike for effortless top-gear overtaking on the road. (Not that most other rival 250s would have done any better...)

As soon as I began to keep the revs up, of course, it was a very different story. The RS came alive at 9000rpm, surging forward smoothly with a banzai shriek, and provided the tacho needle didn't drop below that figure the Aprilia was superbly quick and exciting. If I got Misano's long left curve right, snicked into top just before the next flat-out kink, then tucked my over-large body in as tightly as possible behind the fairing, the little bike would indicate almost 200km/h probably a true 120mph before I had to hit the brakes.

Performance was strong anywhere above 9000rpm, and Aprilia's claim of a 3mph top-speed advantage over the Suzuki (and a three-second edge in back-to-back testing at nearby Mugello) is believable, giving a top speed of 130mph. But dropping below the magical nine-grand figure coming out of a bend meant an age-long delay that would inevitably be recorded by the ever-vigilant on-board timer. Keeping the motor boiling was not easy, either, despite the competent six-speed gearbox. Sometimes, in my enthusiasm for revs, I exited a left-hand bend while desperately trying to get my boot under the gearlever to change up, as the engine ran into a brick wall at the 12,000rpm redline.

Going into a bend was normally less fraught, due mainly to the Aprilia's taut chassis, which is based around a frame and curved swing-arm that look massively strong for the job. Steering response was very good, the bike turning easily without any twitchiness from the front end. Even when used hard on a racetrack, with the superbly powerful and fade-free Brembo brakes standing the Aprilia on its nose, the front end remained well-controlled.

The RS was less impressive at the rear, where the 150/60-section Pirelli Dragon radial wore very quickly, giving an appreciable deterioration in appearance and grip after as little as half an hour's hard riding. Some riders thought the Aprilia's shock was too hard, and that this was overloading the tyre. For my relatively heavy body the spring felt fine, but I'm not convinced the damping matched it. Certainly the bike's rear end deteriorated rapidly once the tyre became worn, giving plenty of slides and a distinct lack of drive out of corners.

Given the opportunity it would have been good to fit a fresh rubber and attempt to fine-tune the shock, but there was no time for this on the launch. Perhaps, as Pirelli's man suggested, the RS is very sensitive to suspension adjustment. But tyre wear is hardly likely to be a problem on the road. There, the Aprilia's inflexible engine would more often be its main drawback as well as part of its charm, for this is a bike that has to be ridden hard and well to be appreciated.

Like the RGV and every other bike of this kind, the RS250 is a singleminded machine that will prove uncomfortable and frustrating on motorways or in town. But in the right hands, on the right road, it will give superbike-humbling performance and as much fun as anything on two wheels. At £5495 it's competitively priced, too, and the 200 bikes that Aprilia Moto UK will import are likely to be snapped up very promptly. The RS looks great, it's quick, and thanks to Aprilia's recent GP exploits it has plenty of street cred too. For dreaming you're Max Biaggi it's magical until the lap-timer brings you back to reality.