Make Model  |      Aprilia RS4 125 | 
|       Year  |      2011 | 
|       Engine  |      Liquid cooled, four stroke | 
|       Capacity  |      124.8 | 
| Bore x Stroke | |
| Compression Ratio | |
|       Induction  |      |
| ECU | |
|       Ignition / Starting  |      / electdric | 
| Clutch | |
|       Max Power  |      16 hp 11.7 kW) @ | 
|       Max Torque  |      |
|       Transmission / Drive  |      6 Speed / chain | 
| Gear Ratio | |
| Frame | |
|       Front Suspension  |      110mm wheel travel. | 
|       Rear Suspension  |      130mm wheel travel. | 
|       Front Brakes  |      Single 300mm discs 4 piston caliper | 
|       Rear Brakes  |      Single 218mm disc 1 piston caliper | 
|       Front Tyre  |      |
|       Rear Tyre  |      |
| Seat Height | 32.3 in | 
|       Wet-Weight  |      120 kg / 264.6 lb | 
|       Fuel Capacity  |      
  
  Aprilia's small supersports bikes have been completely revised. Two models  dedicated for young enthusiasts who want their first experience in the  motorcycling world to be with a proper bike.
* Aprilia RS4 marked a milestone in the evolution of the 125 cc motorcycle.
* For the first time ever, the sportiest bike available for 16 year olds was a  4-stroke.
* For the youngest riders of all, the Aprilia RS 50 embodies all of Aprilia's  technology in a genuine racing replica in just 50 cc.
Aprilia has always been the undisputed leader in the 50 and 125 cc supersports  segment, pioneering innovative concepts and solutions and setting trends for its  rivals to follow.
The Aprilia RS4 125 is the natural successor and most advanced evolution to date  of the Aprilia RS 125, the bike that has dominated the 125 cc sports class for  years, which set the benchmark for the one-eighth litre sports segment and which  is still today the most highly sought after machine among riders competing in  the Sport Production category.
Aprilia RS4 125 introduces the highly advanced, all-new 4 stroke powerplant to  the sports segment, while adopting styling and technical solutions inherited  from the RSV4, the superbike that led Aprilia to victory in the WSBK 2010  championship.
The most significant characteristics of the Aprilia RS 50 and Aprilia RS4 are:
* RS4 125 - single cylinder liquid cooled 125 cc 4-stroke with electronic  injection, 4 valves and double overhead camshafts (DOHC)
characteristics 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
  
  DESIGN
The livery and eye-catching forms of the Aprilia RS 50 and RS4 125 echo the  looks of the Factory version of the Aprilia RSV4 supersports bike. And the RS 50  and RS4 125 share more than just a family resemblance with the most hardcore  street version the bike dominating the world SBK championship.
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 spectacular tapered  tail fairing are identical to their counterparts on 1000 cc supersports model  that set new standards in terms of style and technical content for the superbike  segment.
Extensive aerodynamic studies have minimised surface areas without compromising  wind protection, and the fairings showcase the superlative mechanicals of the  Aprilia RS 50 and Aprilia RS4 125 rather than conceal them. As a result, the  frame and engine are not hidden away but proudly flaunted as fundamental  elements of the design of Aprilia's new small supersports models. With the  triple headlight, the Aprilia RS 50 and RS4 have a decidedly aggressive look  that lends a unique character to the entire front end. The LED taillight merges  stunningly into the ultra-compact tail fairing and offers excellent luminosity.  Even from behind, the Aprilia RS4 125 is absolutely unmistakable.
The product of extensive wind tunnel testing and race experience, the fairing  offers excellent wind protection together with superb aerodynamic efficiency.  And as well as contributing to the extremely aggressive looks of the bike, the  top fairing and tail fairing also maximise performance in terms of speed.
  
  
ENGINES
With the new RS 50 and RS4 125, Aprilia confirms its global leadership in the  small capacity sports bike segment, creating models that exceed the expectations  of even the most discerning rider.
The sophisticated chassis architecture of the Aprilia RS 50 and RS4 125 is  complemented by state of the art engines.
The single cylinder 50 cc unit developed by Aprilia for the RS 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. This state of the art  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.
With a six speed gearbox allowing the rider to make full use of the power  available in all conditions, the Aprilia RS4 offers unbeatable performance in  its class not just in terms of absolute power at high engine speeds, but also in  terms of usable power band, minimised vibration and outstanding mechanical  reliability.
The product of a cutting edge design, the new single cylinder 125 cc unit  features dry sump lubrication making it extremely light and compact, allowing  Aprilia's engineers to develop a class beating chassis layout.
  
  CHASSIS
The RS 50 and RS4 125 stand head and shoulders above the competition for their  superlative chassis layout: developed on the basis of Aprilia's outstanding  successes in WSBK and GP 125, the frame consists of die cast aluminium spars  with crossed reinforcement ribs. With its state of the art design, this  extremely lightweight structure offers exceptional torsional stiffness.
The front suspension also boasts a class beating layout, with a sturdy 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.
Both the Aprilia RS 50 and RS4 125 boast class beating brake systems: 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.
STANDARD EQUIPMENT AND FEATURES
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.
On Aprilia RS4, one additional detail underscores the level of sophistication of  the bike: the exhaust, which is unmistakably inspired by competition machines,  is completely integrated within the lower part of the fairing. A solution that  is not just visually effective, but which also contributes significantly to the  dynamics of the bike by helping to centralise masses.
The passenger saddle is yet another example of the extreme level of  sophistication of these new bikes from Aprilia. Instead of fiddly screws, a  practical quick release button allows the passenger seat to be exchanged with  the tail fairing cover in an instant to transform the bike from two seat to  single seat configuration
  
  
  
