Aprilia RX 125 (2008-2012): A Two-Stroke Enduro Icon Revisited

Introduction

The Aprilia RX 125, produced between 2008 and 2012, remains a cult favorite among off-road enthusiasts and young riders cutting their teeth in the dirt. Designed as a gateway to the world of enduro riding, this Italian machine blends race-bred technology with approachable dynamics. After spending a day thrashing a well-preserved 2010 model through rocky trails and tight forest paths, it’s clear why this bike still commands respect. Let’s dive into what makes the RX 125 a standout in its class.

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Design & Ergonomics: Pure Functionality

The RX 125’s design screams purpose. With its angular bodywork, minimalist plastics, and steel double-cradle frame, this bike is built to survive abuse. Aprilia’s styling borrows heavily from its championship-winning RXV line, giving the RX a "big bike" aesthetic despite its compact size. The narrow profile and aggressive seat-to-tank transition make it easy to shift weight during technical riding.

Key Highlights:
- Seat Height: Adjustable from 830 mm (32.7") to 925 mm (36.4"), catering to shorter riders without sacrificing ground clearance.
- Weight: At 116 kg (256 lbs) dry, it’s remarkably flickable. Lifting it out of mud or pivoting mid-corner feels effortless.
- Fuel Capacity: 10 liters (2.6 US gal) with a 1.3L reserve—enough for 2-3 hours of hard riding.

The digital dashboard (a rarity in 125cc bikes of this era) provides essential data like speed, RPM, and fuel level. While not flashy, it’s legible under harsh sunlight—a thoughtful touch for enduro use.

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Engine Performance: Two-Stroke Thunder

The heart of the RX 125 is its liquid-cooled, single-cylinder two-stroke engine. With 124.8cc displacement and a Nikasil-coated aluminum cylinder, this powerplant is both robust and rev-happy.

By the Numbers:
- Power: 21.5 HP (15.7 kW) @ 9,500 RPM
- Torque: 16 Nm (11.8 lb-ft) @ 8,000 RPM
- Top Speed: 120 km/h (75 mph)

Firing up the RX 125 via its kickstarter (no electric start here) delivers an instant nostalgia hit. The Dell’Orto VHST 28 carburetor barks to life with that signature two-stroke rasp. On the trail, power delivery is crisp and linear. The 6-speed gearbox is slick, with a closely spaced ratio ideal for technical climbs. Sixth gear cruises comfortably at 90 km/h (56 mph), though the engine feels strained beyond 100 km/h (62 mph).

Euro 3 Compliance:
Aprilia’s engineering shines in balancing performance with emissions standards. The separate oil mixing system (with a volumetric pump) ensures precise lubrication without the hassle of premixing fuel.

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Handling & Suspension: Born for the Dirt

Where the RX 125 truly excels is in its chassis setup. The combination of a high-strength steel frame and premium suspension components creates a bike that’s both stable at speed and nimble in tight sections.

Front Suspension:
- 40mm inverted forks with 260mm (10.2") of travel. Plush over roots and rocks, yet firm enough to handle jumps.

Rear Suspension:
- Steel swingarm with a piggyback monoshock offering 270mm (10.6") of travel. Preload adjustment is a must for heavier riders.

Brakes:
- Front: 260mm disc with twin-piston caliper. Bite is strong but progressive.
- Rear: 220mm disc with single-piston caliper. Easy to modulate for controlled slides.

Wheels & Tires:
- Front: 90/90-21 knobby tire on a 21" spoked wheel—excellent for tackling ruts and loose terrain.
- Rear: 120/90-18 tire provides predictable traction even on slick mud.

During testing, the RX 125 carved through berms like a bike twice its price. The upright riding position and wide handlebars inspire confidence, while the narrow seat lets you shift weight effortlessly.

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Competition: How Does It Stack Up?

The 125cc enduro segment is fiercely competitive. Here’s how the RX 125 compares to its rivals:

1. Yamaha WR125R:
2. Pros: Four-stroke reliability, fuel injection, lower seat height (880mm/34.6").
3. Cons: Heavier (129 kg/284 lbs), less peak power (15 HP).

4. Verdict: The WR125R is better for commuting, but the RX 125 dominates off-road.

5. KTM 125 EXC:

6. Pros: Lighter (105 kg/231 lbs), higher-spec suspension (WP components).
7. Cons: Requires frequent top-end rebuilds, pricier maintenance.

8. Verdict: The KTM is a race-ready weapon, but the Aprilia offers better value.

9. Husqvarna TE 125:

10. Pros: Chromoly frame, hydraulic clutch, six-speed gearbox.
11. Cons: Softer suspension setup, less aggressive powerband.
12. Verdict: The Husky is a close match, but the RX 125’s two-stroke character gives it an edge.

Aprilia’s Advantage: The RX 125 strikes a unique balance between playful two-stroke power and user-friendly ergonomics. It’s a bike that forgives rookie mistakes but still rewards skilled riders.

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Maintenance: Keeping the RX 125 Alive

Owning a two-stroke enduro bike requires diligence. Here’s what RX 125 owners need to know:

1. Engine Care:
2. Piston Rings: Replace every 50-60 hours of hard riding.
3. Nikasil Cylinder: Resilient but can wear if oil mixture is incorrect. Use a 1:50 ratio with synthetic two-stroke oil.

4. Carburetor: Clean the Dell’Orto VHST 28 every 20-30 hours. Consider upgrading to a JD Jet Kit for altitude adjustments.

5. Suspension:

6. Change fork oil annually. For aggressive riders, MOTOPARTS.store offers aftermarket springs ($120-$180) tailored to your weight.

7. Chain & Sprockets:

8. The OEM chain lacks durability. Swap to a DID 520ERV3 Gold Chain ($90) and steel sprockets for longevity.

9. Brakes:

10. EBC sintered brake pads ($35-$50) improve stopping power in wet conditions.

11. Upgrades Worth Considering:

12. Exhaust: A DEP two-stroke pipe ($250) adds mid-range punch.
13. Air Filter: Twin Air foam filter ($25) with pre-cleaner boosts airflow.
14. Handguards: Acerbis Rally Pro guards ($70) protect levers during crashes.

Pro Tip: Always carry a spark plug wrench and spare plug—two-strokes can foul plugs if idled too long!

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Conclusion: A Timeless Off-Road Companion

The Aprilia RX 125 isn’t just a motorcycle; it’s a rite of passage. Its razor-sharp handling, addictive powerband, and bulletproof build make it a joy to ride even a decade after its release. While modern four-strokes have stolen the spotlight, the RX 125 reminds us why two-strokes remain irreplaceable in the dirt.

For owners looking to enhance their RX 125, MOTOPARTS.store stocks everything from performance upgrades to OEM replacements. Whether you’re chasing podium finishes or weekend adventures, this Aprilia deserves a spot in your garage—and our parts deserve a spot on your bike.

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Specifications sheet

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