GoogleCustom Search

2008 Aprilia RS125

2008 Aprilia RS125 

The RS 125 is the undisputed leader among 125 cc supersports. Aprilia has always led the field in lightweight sports bikes, pioneering new concepts and advanced solutions, and developing technology that others have had to struggle to follow. Like all Aprilia sports motorcycles, the RS 125 has benefited from the sophisticated technology that has been developed over years of success in GP racing, and quickly transferred into production. Over the years, the RS 125 has forged a reputation as the standard setter for sports 125’s. Sales success has come naturally too, with the RS 125 topping the sales tables on all European markets. The RS 125 is the inevitable choice of riders entering Sport Production racing. And rightly so, because when the competition gets tough, there is simply no other bike like the Aprilia RS 125.

The Aprilia RS 125 is designed and built for technical supremacy and has the looks to match. Its graphics are totally new and based entirely on those of the bike that dominated the 2006 250 GP world championship.

The Aprilia RS 125 gives young riders the best the market has to offer in terms of components and equipment, with a concentration of technical refinements that are not found on many superbikes.

The following are just some of the main features of the Aprilia RS 125.

  • Tried and tested yet extremely sophisticated Rotax two stroke engine.
  • Super-rigid aluminium frame and swingarm derived from Aprilia’s vast GP experience.
  • Upside down fork.
  • Front brake with radial caliper and four opposed pistons.
  • RSV 1000 R style fairing, windshield and tail.
  • RSV Factory style, crossed spoke wheels.
  • Analog/digital instrument panel with multi-functional computer.
  • RSV Factory style, forged steering yoke.
  • Oval section racing silencer with riveted end plates.

The mean, cutting edge look of the new RS 125 tells you that this is a professional racing machine. The styling of the RS is based on that of the RSV 1000 R and, as with all Aprilia sports bikes, is the result of painstaking aerodynamic research. The fairing, for example, was perfected by extensive wind tunnel testing, to guarantee GP class wind protection and minimum drag for maximum racetrack efficiency. The fairing, windshield and tail not only look mean and aggressive, but allow the RS 125 to reach a blistering top speed, eliminating all turbulence around the rider. Man and machine really can become one when the machine in question is an Aprilia RS 125.

The latest generation twin halogen headlight also adds to the mean look of the new RS 125, and delivers a high power light beam for enhanced visibility and safety at night.

The sleek tail looks exactly like the tail of a GP racer. Thanks to the effort put into the design of the RS 125’s tail, not even the passenger seat disturbs the bike’s impeccable lines.

The crossed spoke wheels are not only lighter and more stylish, but safer and more reliable too.

The powerful but reliable, single cylinder, two stroke, Rotax-Aprilia engine needs no introduction. Over the years it has won a reputation for being unbeatable on the track and dependable on the road. Still today, this engine boasts technical solutions that are state-of-the-art for two strokes, including a crankcase reed valve intake, liquid cooling, an anti-vibration balancer shaft, and an automatic mixing system. The RS 125’s engine has been constantly updated over the years to keep in line with the latest emission control legislation without penalising performance. A catalytic converter and precision carburation has won Aprilia’s single cylinder two stroke homologation to Euro 3 standards. And the amazing thing is that this has been achieved without losing out on performance: the Aprilia RS 125 engine remains the reference point for all 125 cc powerplants.

Without a doubt, the most advanced single component on the RS 125 is its frame. Developed from Aprilia’s vast experience in GP 125 racing, the RS 125 frame is made from cast aluminium alloy with cross-ribbing reinforcement. Despite its extremely light weight, this advanced structure achieves amazing torsional rigidity, setting the standards for Aprilia’s competitors.

The box section, aluminium alloy swingarm has the highest torsional rigidity of all production 125 cc swingarms. Differential side members enable the exhaust to follow a path that maximises engine performance and enables more acute angles of lean to be achieved on bends without risking dangerous contact with the asphalt.
The suspension too plays a fundamental role in ensuring not only the RS 125’s performance, but its safety and comfort too. The RS 125 can rely on an upside-down fork that has been optimised for maximum performance on the racetrack while also delivering a more satisfying ride on public roads.

The rear suspension features rising rate linkages based on Aprilia’s 125 GP racing technology, for excellent traction and superb comfort even over uneven road surfaces. The hydraulic monoshock that provides the damping for the swingarm is also adjustable in spring preload.

Like any self-respecting supersport motorcycle, the RS 125 has to have the best when it comes to components. The braking system is brand new, and designed for maximum efficiency under competitive riding conditions. The front brake is a genuine state-of-the-art, high performance system with a radial caliper and four opposed pistons. In addition to the 320 mm front disc, the system also incorporates a radial master cylinder and aeronautical hoses for maximum precision and unrivalled braking power. The rear disc is 220 mm in diameter and is also equipped with metal braided hoses for perfectly balanced, high performance braking.

The world’s top racing 125 obviously deserves top quality equipment. In addition to a high-tech chassis, the Aprilia RS 125 benefits from the most prestigious components available. The compact and lightweight, latest generation instruments are derived from those of the RSV 1000 R and include an analog rev counter and a multifunctional digital display incorporating an on-board computer that can be operated directly from the handlebars. To keep everything under control, the instrumentation includes a speedometer, rev counter, coolant temperature gauge and a racing chronometer. The system even has provision for interfacing with the optical finishing line devices found at many racetracks.

The latest colour schemes have been chosen to enhance the Aprilia RS 125’s aggressive styling. The classical Aprilia Black, the Red fluo, and the exclusive Replica Spain’s N.1.

A power kit, designed exclusively for racetrack use, is also available as an optional accessory to achieve the full potential of this amazing two-stroke engine.
The kit includes:

  • racing expansion chamber exhaust
  • complete racing exhaust valve
  • control unit and solenoid for racing exhaust valve
  • needle, main jet and atomiser for full power carburation
  • racing spark plug



Liquid cooled, single cylinder two stroke. Aluminium cylinder with Nikasil coated liner. Read valve intake. Separate lubrication. Homologated to Euro 3 standards.

Bore by stroke

54 x 54.5 mm.


124.8 cc.

Compression ratio

12.5 ± 0.5:1.


Dell’Orto VHST 28.


Electronic CDI ignition.




12 V – 180 W


Separate mixing with variable displacement, volumetric pump.


6 speed.
1st 10/30 (0.33)
2nd 14/29 (0.48)
3rd 17/27 (0.63)
4th 19/25 (0.76)
5th 21/24 (0.87)
6th 22/23 (0.67)

Primary drive

Gearbox: 63/19 (3.31).

Final drive

Chain: 17/40 (2.35).


Multi-plate in oil bath.


Sloping twin-spar frame in thin wall box section cast aluminium, with reinforcement cross-ribbing.

Front suspension

Upside down hydraulic fork, Ø 40 mm. Wheel travel 120 mm.

Rear suspension

Swingarm with asymmetric members in thin wall box section cast aluminium. Hydraulic monoshock with adjustable spring preload. Wheel travel 120 mm.


Front: Floating Ø 320 mm disc. Radial caliper with four differential diameter pistons, Ø 32 mm – Ø 27 mm.


Rear: Single Ø 220 mm disc. Caliper with two Ø 30 mm pistons.


Aluminium alloy. Front 3.00 x 17”; rear 4,00 x 17”.


Tubeless radial. Front 110/70 17”; rear 150/60 17”.


Overall length 1955 mm
Overall width (at handlebars) 720 mm
Overall height (at windshield) 1100 mm
Seat height 805 mm
Wheelbase 1345 mm


14 litres (3.5 litre reserve).


Aprilia Black, Red Fluo, Replica Spain’s N.1

The 21 kW RS 125 (sold on the German market) is still equipped with a Dell’Orto PHBH 28 carburettor and is homologated to Euro 2 standard.