The Aprilia RSW 250 in detail

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The Aprilia RSW 250 in detail

Brilliant parade

Into the box, roll gate down ?? Factory machines are reluctant to be peeped behind the cladding. MOTORRAD was exclusively allowed to remove the leaves from Ralf Waldmann’s factory Aprilia, which was shiny in aluminum silver and carbon gray.

Ordinary people like to take it easy. Sepp Schlogl is not an ordinary person. Oven world titles as chief mechanic in the service of the legendary Toni Mang and a whole bunch of vice world championships show that the Bavarian knows how to work on racing engines. And he likes to do it.

But since the team around team boss Dieter Stappert and his driver Ralf Waldmann as well as Klaus Nohles, the newcomer for the year 2000 – switched from Honda to Aprilia at the beginning of last season, the Bavarian has often been involuntary idleness. “The Aprilia is perfect. There is hardly anything left for us to do, "says the tuner legend, imaginatively taking off his hat to Aprilia race engineer Jan Witteveen.

The success of the Aprilia RSW 250 proves that the concept is right: five 250 World Championship titles in the past six years. The engine design already deviates from the norm. Although the engine looks like an ordinary V-twin cylinder, the Aprilia unit is actually a tandem engine with a 90 degree cylinder angle. Instead of a common crankshaft for both pistons, this construction principle uses two separate crankshafts coupled via a gearwheel with two separate crankcases. The advantage: The mixture supply for each cylinder can be specified more individually and therefore more precisely. The counter-rotating crankshafts due to this concept also make an additional balancer shaft unnecessary, as in the Yamaha or Honda V2 Production Racers. In the meantime, Honda has at least followed with the factory engine and adopted the tandem version ?? however with membrane inlet as before.

In contrast to Aprilia, which is the only manufacturer in the GP scene to use rotary valve inlet control. With this construction principle, two flat slide carburettors made of feather-light magnesium feed the crankcase more aerodynamically from the engine side. Master Schlogl can still let off steam when tuning the carburetor. Dozens of different nozzles, nozzle holders, needles and power jet nozzles result in an almost infinite number of possible combinations. Those who want to be used should have a maximum output of almost 100 hp in all weather and on every slope. Helpful: sensors for the temperature of the titanium exhaust system and the tendency to knock give objective recommendations in addition to the piston image.

Adjusting, setting, changing – despite all the perfection, Aprilia can only offer the basis for fine-tuning on site. Example gearbox. Eight different gears per gear are stacked on the shelves of the racing transporter. The longest gear ratio is good for 171 km / h in first gear and 272 km / h in sixth. The complete switch box, a cassette gear that can be removed from the side of the motor housing, can be changed in 30 minutes.

Even with the chassis, only the finest is on the wheels. For example, the suspension strut and upside-down fork from Ohlins. Carbon stanchions save 600 grams of weight compared to aluminum tubes and twist less when braking hard. Speaking of braking. In the fast-paced GP business, the only brakes are light, high-heat-resistant carbon fiber brake discs. Unit price for a 255 disc: 8,000 marks. Lifespan: half a season after all. In the rain, however, the carbon stoppers do not reach the required operating temperature, so steel disks have to be converted when it is wet. They only cost a tenth, but are down after one race.

Aprilia gains a decisive advantage through connections to Formula 1. Ferrari engineering supplies the Venetier exclusively in the GP scene with carbon wheels. A weight saving of almost one kilogram per bike makes handling easier, but strains the budget. For the annual leasing fee for ten noble bikes, 80,000 marks have to be made loose.

Carbon theme. Black-gray sheen wherever you look. The complete rear frame, the tank, the fairing, the front fender and the airbox ?? everything from the carbon fiber braid. Even the double swing arm. For greater rigidity, it is also designed as a single molded part with the rear wheel cover.

In this noble environment, the barely visible adjustment options for the chassis appear almost profane. Eccentric bearing shells for the steering head bearing allow the steering angle to be varied by 0.5 degrees, further eccentrics in the magnesium fork bridges change the fork offset by up to 2.5 millimeters. Not to mention the freely selectable overhang of the bars in the fork bridges and the stepless height adjustment of the shock absorber.

D.if a high-tech racer like the Aprilia also challenges the driver, Ralf Waldmann also has to learn. Like Tetsuya Harada or Loris Capirossi before him, the Ennepetal is only gradually getting to grips with the capricious prima donna, even in his second year at the RSW. In this respect, two GP victories and fifth place in the World Championship still give hope for greater deeds.

Grand Prix regulations

Despite the increased popularity of the Superbike World Championship, which is held with near-series four-stroke engines, the Road Grand Prix continues to be the world’s most sporty motorcycle racing series. The GP scene is traditionally divided into three classes: 125 cm3 (maximum one cylinder) in which Aprilia, Honda and the Spanish Derbi set the tone; 250 cc (maximum two cylinders) with Aprilia, Honda and Yamaha as competitors; 500 cm3 (maximum four cylinders), where Honda, Suzuki and Yamaha celebrate victories. The sidecar class dropped out of the GP program in 1997 and has only been held as a World Cup since then. Starting in 2002, the world motorcycle association FIM plans to open the previous 500cc class, which like all GP classes is contested exclusively with two-stroke engines, also for four-stroke machines designed largely without technical restrictions ?? even if those who know the racing scene predict skyrocketing costs and the demise of private or semi-official teams.

Technical specifications

ENGINE Water-cooled two-cylinder tandem engine, cylinder angle 90 degrees, electronic exhaust control, approx. 100 HP at 12,950 rpm, bore x stroke 54 x 54.5 mm, two Dellorto flat slide carburettors with Powerjet, 0 42 mm, mixture lubrication 1:25, six-speed -Cassette transmission with ignition interrupt CHASSIS Aluminum bridge frame, upside-down fork from Ohlins with carbon stanchions, sliding tube diameter 42 mm, magnesium fork bridge above, welded hollow-chamber aluminum fork bridge below, carbon rear wheel swing arm in monocoque construction, Ohlins double disc spring strut operated via deflection Front with four-piston fixed caliper, brake discs made of carbon fiber, 0 255 mm, single disc brake with two-piston fixed caliper at the rear, brake disc made of steel, 0 218 mm, wheelbase 1320 mm, steering head angle 61.5 ± 0.5 degrees, tank capacity 23 liters, weight without Petrol 96.5 kg.

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