2011 Aprilia RS4 125cc And RS4 50cc

Tuesday, November 2nd, 2010

by Mark

It seems small bikes, either sports or otherwise, are all the rage at this years EICMA.

Aprilia have created what they dub as two models for young riders looking for their first experience with a proper bike.

The Aprilia RS4 is a 125cc 4-stroke and there’s also the Aprilia RS4 50 2-stroke which Aprilia say is a genuine racing replica in just 50 cc.

The Aprilia RS4 125 contains the all-new 4 stroke engine with electronic injection, 4 valves and double overhead camshafts (DOHC), whilst adopting styling and technical solutions from its big brother the RSV4, the superbike that led Aprilia to victory in the World Superbike Championships.

Characteristics that both bikes have in common:

• extremely stiff aluminium perimeter frame derived from racing experience
• 41 mm upside down fork
• front brake with 300 mm disc and radial four piston calliper
• Superbike inspired analogue/digital instrument panel
• fairings derived directly from RSV4 project for total aesthetic coherence with the SBK world champion

The design of the fairings and tank, the unique looks of the front end, with the headlights suspended over the gaping air intakes, and the tapered tail fairing are identical to their counterparts on 1000 cc supersports model.

There’s a triple headlight, LED taillight and an ultra-compact tail fairing.

The single cylinder 50 cc unit developed by Aprilia for the RS4 50 is a water cooled two-stroke with reed valve induction. The lubrication uses a separate mixing system with a variable capacity volumetric pump. The six speed gearbox lets the rider make full use of the performance of this class beating engine.

The Aprilia RS4 is powered by an all new 125 cc water cooled 4 stroke single cylinder engine with four valves and electronic engine boasting a sophisticated double overhead camshaft (DOHC) valve timing system. The engine produces the maximum power output permitted for the class with a smooth, linear delivery and ecologically - as it meets even the strictest emissions regulations in effect.

The front suspension has a 41 mm upside fork, red anodised stanchion clamps and a wheel travel of 110 mm, while at the rear is a monoshock linked directly to the asymmetric swingarm.

Each bike uses a 300 mm steel disc at the front, gripped by a four piston radial calliper, and a 220 mm disc at the rear with a single piston calliper.

The 17” wheels are shod with 100/80 rubber up front and a 130/70 tyre at the rear.

The multifunctional analogue/digital instrument panel with LCD display draws directly from Aprilia’s experience in the Superbike class. The split 6-spoke design of the wheels further emphasises the purposeful character of Aprilia’s latest small capacity sports bikes.

Aprilia RS4 50 - Technical Specifications

Engine type	Single cylinder, 2 stroke, liquid-cooled
Bore and stroke	39.86 x 40 mm
Engine capacity	49.9cc
Compression ratio	11.5 :1
Carburettor	Dell’Orto PHVA – 17.5
Ignition	Electronic C.D.I.
Starting	Electric
Battery	12V – 6Ah
Lubrication	Automatic mixer
Gearbox	6 speeds, I 11/34, II 15/30, III 18/27, IV 20/24, V 22/23, VI 23/22
Primary drive	Gears, 21/78
Final drive	Chain, 11/53
Clutch	Multidisc
Exhaust system	Euro 2
Frame	Twin spar aluminium frame
Front suspension	41 mm upside down fork, wheel travel 110 mm
Rear suspension	Asymmetric swingarm with monoshock, wheel travel 130 mm
Brakes	Front: 300 mm stainless steel disc with radial 4 piston calliper
Rear:	218 mm stainless steel disc and calliper with single 25 mm piston
Wheel rims	In light alloy with 6 split spokes, with sealing profile for tubeless tyres; front: 2.75 x 17″; rear: 3.50 x 17″
Tyres	Front: 110/80 - 17″, rear: 130/70 - 17″
Dimensions	Max. Length 1953 mm
Max width	740 mm
Max height	at top fairing 1,138 mm
Saddle height	820 mm
Wheelbase	1,350 mm
Fuel tank capacity	14.5 litres