2009 Aprilia RX 125/SX 125

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Aprilia carries on the production of their latest Supermoto and Enduro 125cc models, the SX 125 and RX 125, in 2009. Currently not new in the lineup, but radically improved, the models announced a whole new kind of fun both on dirt tracks and on paved ones with the occasion of last year’s revision. Now, we got the chance to swing a leg over each model and couldn’t be more impressed, given the category.



Dedicated to today’s demanding young sports riders, the Aprilia RX and SX 125 incorporate many of the features that have contributed to the amazing success of the RXV and SXV . These two stylish, high performance motorcycles set new standards for the 125cc dirt bike market.


Aprilia RX 125/SX 125

RX is a historical name for Aprilia. Over the years, the RX designation has graced machines with amazing performance, real ‘schools on wheels’ for young enthusiasts learning the ropes in off-road riding and racing. The new RX might not be an extreme enduro but it is perfectly able to tackle even the most challenging off-road circuits. The RX even has something of a double personality, because as soon as you get back on the road, it is equally happy as a daily commuter.


Aprilia RX 125/SX 125

Aprilia was the first manufacturer to introduce unique and dramatically innovative design to essential enduro and motard motorcycles. In the same way in which the RXV and SXV have become style icons in their own right, the SX and RX are also destined to leave their mark on young off-road riders. As with any self-respecting off-road machine, the design of these bikes is dedicated to total functionality and efficient control. Their styling leaves no room for frills and gadgets. With their unmistakable lines, the SX and RX are simply unique among off-roaders.

Aprilia RX 125/SX 125

The RX and the SX share a clear Aprilia family look, obviously inspired by their big sisters, machines that have established a whole new trend in off-road design.


Aprilia RX 125/SX 125

The small RX and SX models suffer the direct influence of their RXV and SXV siblings. The world-beating styling, performance and technology of these fantastic machines were obviously destined to engender a family of eye-catching and modern off-road motorcycles. The SX 125 and RX 125 are the entry-level off-road machines from Aprilia. Specialized and refined, they are the obvious choice for young riders who want to stand out from the crowd.

The SX and RX are both built to deliver total rider satisfaction. Though the technology is basically the same, it has been adapted to match the different specialities. The SX and RX 125 share the same body, frame, engine and suspensions but their characters suit very different passions.

The 125 cc single cylinder engine is a state-of-the-art two-stroke unit. It is a classic example of how race-developed technology can deliver extremely low emissions as well as top performance. On the RX 125 and SX 125, Aprilia has succeeded in perfecting its two stroke design to bring it in line with the strict new Euro 3 standard without any loss of performance or riding satisfaction. This sparkling single cylinder engine easily develops the maximum permitted power for its class, with all the lightness and zippy acceleration typical of a high performance two-stroke.

This engine has already established a place for itself in the hearts of 125 fans, thanks to its many advanced characteristics, including liquid cooling, and a balancer shaft. The cylinder has a nickel silicon carbide (Nikasil) liner for an ultra-reliable, extended life. Lubrication is provided by a separate mixer system.

Active safety on the Aprilia RX and SX is ensured by advanced suspension and a braking system that sets new standards for stopping power and progressive action. The front brakes feature a 260 mm disc and two-piston floating caliper while the back brake incorporates a 220 mm disc and another floating piston.

Aprilia RX 125/SX 125

The robust, steel, double cradle, trellis frame is coupled to an over-sized suspension system. At the front is a mighty, 40 mm upside down telescopic fork offering wheel travel of 260 mm.

With its 17” wheels and sports tires, the SX is the obvious candidate for the meanest 125 over mixed routes award. Nippy and lightweight, the SX delivers real ‘big bike’ performance without exceeding the power restrictions imposed by law. Its refined, sprightly engine never lets you down, even when ridden to the limit on a racetrack.

At the back, the long steel swingarm used to obtain maximum traction is damped by a prestigious hydraulic monoshock with piggy back cylinder. Rear wheel travel is 270 mm.

Specialist machines like the RX and SX demand top quality components. The wheels, for example, are fundamentally important to this type of motorcycle, having to combine the contrasting properties of strength and lightness. The RX and SX are equipped with aluminum wheels. The RX is fitted with a classic enduro racing front wheel of 21” in diameter and a 90/90-21” tire for fantastic grip on all sorts of surface. The 18” rear wheel is fitted with a 120/90 tire, again in keeping with the best off-road traditions.

Just like top sports motards, the SX boasts lightweight 17 inch, wide profile wheels and generous sports tires, 110/70-17” and 150/60-17” for maximum grip under all conditions.

Test Ride

Starting from these facts stated by Aprilia, we got down to business on these similar and yet totally different pieces of Italian engineering.

RX 125

Aprilia RX 125/SX 125

Here at TopSpeed, we always find an excuse to get ourselves muddy from head to toes, so the Aprilia RX 125 was the first one we asked for. We did get a change to ride it around town for a little while and also on the highway (on the way to the trails) and have to say that it feels very light and maneuverable. The engine has the rarely heard two-stroke sound, which means that people will still be turning their heads after you, and does its job of delivering a fairly wide spread of power smoothly. Things do get interesting when opening up the throttle more than the riding instructor would recommend, but the bike remains overall user-friendly on the streets. The strong wind blast and the narrow seat don’t contribute at the commuting side of the bike, making it adequate for short distances only.

The fun part begins once the Pirelli dirt rubber loses the asphalt in favor of gravel, rocks and, of course, dirt. Suddenly, the riding position doesn’t feel like a killer any more and the two-stroke engine unveils its racy nature. Being a two-stroke, it requires revs in order to deliver the best of it and we jure gave what it required. We’ve gone for unlimited power and we must say that the 21.5 hp translates in plenty to work with. The bike is happy climbing hills and jumping over obstacles, but also when going for top speed (we have to admit that we did that on the highway). The six-speed gearbox is of much help when doing so, but also in general because the rider soon finds that being in the right gear is of the essence in order to properly exploit the 21.5 hp.

Aprilia RX 125/SX 125

No matter the challenge, the small RX resists well to abuse. The suspension is tuned for off-road use, so landings and riding over bumps is called routine. We did manage to hear the fork bottoming out during a near crash situation, but not when performing the usual stuff, which includes climbing rocks, jumping over logs, passing through rivers and jumping our way down to the most challenging places to get out of.

In the woods, this bike is well at home and it once again shows how versatile it actually is. We thought that teenagers are the main target of the Aprilia RX 125, but now came to find that all people with a taste for adventure are.

SX 125

Aprilia RX 125/SX 125

While the Aprilia SX 125 is much similar to its enduro brother, it manages to offer a whole different ride from the first time you through a leg over it. Supermoto requires sharp handling, precision, instant throttle response and also versatility, so it was all up for this different pair of wheels to prove? Apparently yes!

This different small blast does require a little bit of getting used to, but it unveils a sporty character afterwards. The low center of gravity is an advantage around sharp corners, when the rider’s boot scraps the pavement and the good engine response helps at getting out of corners fast.

Although it won’t scare anyone, the engine’s power is sufficient for starting riders to work with, but unlike its enduro sibling, the SX won’t prove efficient for riders who are more experienced. We rarely got to use fifth gear on the supermoto track, but did enjoyed lifting up the front wheel with every occasion that we had and we must say that the bike manages to do that quite easily.

Aprilia RX 125/SX 125

The bike is fun to ride and very confidence inspiring. We just loved sliding that rear wheel in and out of corners while working the brakes and preparing to open up the throttle. It is quite fast, despite the cylinder capacity (remember that this is a two-stroke) and retains that versatile feel. You get to notice that when riding on the dirt portion of the track, but also when actually taking the thing on the streets. It does just fain in industrial areas, where you get to jump a lot with it, make wheelies and burnouts.


Aprilia RX 125/SX 125

Two-stroke motorcycles aren’t very popular nowadays, but it is nice to see that one manufacturer still does its best in improving the ride quality of two-wheelers still powered by this type of engine.

Because diversity is always the solution for bringing in new customers, Aprilia’s enduro and super motard are sure to meet various rider requests and so make sure that we’ll be seeing them on the market a long time from now.



Engine and Transmission

Aprilia RX 125/SX 125

Type: Rotax 122 single cylinder 2-stroke. Aluminum cylinder with Nikasil liner.

Displacement: 124.8 cc

Cooling: Liquid cooled.

Bore: 54 mm

Stroke: 54.5 mm

Compression ratio: 12.5:1

Intake: Reed valve.

Fuel system: Dell’Orto VHST 28 carburetor.

Lubrication: Separate mixing with variable displacement, volumetric pump.

Fuel: Unleaded petrol.

Starting: Kick start.

Ignition: Electronic CDI ignition.

Alternator: 12 V – 180 W.

Max. power at crank: 11 kW; 16 kW.

Max torque: 12.2 Nm @ 8000 rpm (11 kW); 16 Nm @ 9750 rpm (16 kW).

Gearbox: 6 speed.


1st 10/30

2nd 14/29

3rd 17/27

4th 19/25

5th 21/23

6th 22/21

Primary drive: Helical gears. Ratio: 19/63.

Final drive: Chain. Z 16 gearbox pinion, Z 45 rear wheel sprocket (11 kW); Z 15 gearbox pinion, Z 45 rear wheel sprocket (16 kW).

Clutch: Multi-plate wet clutch.

Chassis and Dimensions

Aprilia RX 125/SX 125

Frame: High strength steel frame with double trellis beam and double cradle. Detachable seat frame.

Front suspension: 40 mm upside down hydraulic fork. Wheel travel 260 mm.

Rear suspension: Steel swingarm. Hydraulic monoshock with piggy back cylinder. Wheel travel 270 mm.

Front brake: 260 mm disc. Floating caliper with two parallel pistons.

Rear brake: 220 mm disc. Floating caliper with single piston.

Front wheel: Aluminum, 1.6x21”.

Rear wheel: Aluminum, 2.15x18”.

Front tire: Pirelli MT21, 90/90x21”.

Rear tire: Pirelli MT21, 120/90x18”.

Overall length: 2,255 mm.

Overall width (at brake levers): 850 mm.

Overall height (at mirrors): 1,415 mm.

Seat height: 925 mm.

Wheelbase: 1,480 mm.

Dry weight: 116 Kg.

Fuel tank capacity: 10 liters (including 1.3 liters reserve).


Top speed: 115 kph (11 kW); 120 kph (16 kW).

Versions: 11 kW and 16 kW.

Emissions: Euro 3 (11 kW and 16 kW).

Instrumentation: Essential multifunctional panel.

Color schemes: White Off / Off Black.


I always like two stokes bikes by reading the test riding you guys did this 125 looks like fun.smiley

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