Aprilia RS4 125 Replica [2011–2017]: A Gateway to Superbike Thrills

Introduction

The Aprilia RS4 125 Replica isn’t just a motorcycle—it’s a statement. Designed as a bridge between youthful enthusiasm and professional-grade engineering, this 125cc sportbike dominated the entry-level sport segment from 2011 to 2017. Born from Aprilia’s World Superbike legacy, the RS4 125 Replica mimics the aggression of its bigger sibling, the RSV4, while offering accessibility to riders restricted by licensing laws or seeking a lightweight, agile machine.

With its aluminum perimeter frame, liquid-cooled 4-stroke engine, and track-inspired ergonomics, the RS4 125 Replica is a masterclass in balancing performance and practicality. This review dives into what makes this bike a standout choice for new riders and seasoned enthusiasts alike, dissecting its design, performance, and how it stacks up against rivals.

Design: Small Bike, Big Presence

The RS4 125 Replica borrows its DNA directly from Aprilia’s championship-winning RSV4. From its triple-LED headlights suspended over gaping air intakes to its razor-sharp tail section, this bike looks like a shrunken superbike. Aerodynamic fairings, tested in wind tunnels, minimize drag while showcasing the engine and frame rather than hiding them—a design philosophy that screams confidence.

Key Design Features:
- Aggressive Styling: The GP-inspired tail, twin-projector headlights, and underbelly exhaust (integrated into the fairing) mirror the RSV4’s aesthetic.
- Aluminum Perimeter Frame: Lightweight yet rigid, this frame provides the backbone for precise handling.
- Ergonomics: The 820 mm (32.3-inch) seat height suits shorter riders, but the rearset pegs and clip-on bars enforce a committed riding posture.
- Color Options: Over the years, Aprilia offered bold schemes like red/silver/black, racing black/white, and even Max Biaggi-inspired replicas.

The RS4’s compact dimensions (1,955 mm long, 740 mm wide) and 120 kg (264.5 lbs) wet weight make it nimble, while the 14.5-liter (3.8-gallon) fuel tank ensures practicality for daily rides.

Engine Performance: The 4-Stroke Revolution

Aprilia’s shift from 2-stroke to 4-stroke engines marked a turning point for the RS4 125. While purists mourned the loss of raw power, the 124.8cc DOHC 4-valve engine brought reliability and a broader powerband—critical for both city commutes and track days.

Specifications:
- Power: 15–16 HP (11–11.7 kW) @ 10,500 RPM
- Torque: 10.9 Nm (8.0 lb-ft) @ 8,250 RPM
- Fuel System: Electronic fuel injection (32 mm throttle body)
- Cooling: Liquid-cooled for consistent performance

Riding Experience:
The engine thrives in the upper rev range. Below 7,000 RPM, it’s docile, perfect for navigating traffic. Crack the throttle past 8,500 RPM, and the single-cylinder comes alive, pulling smoothly to its 11,500 RPM redline. The 6-speed gearbox is crisp, though the optional quick-shifter (a rarity in this segment) elevates the experience, allowing clutchless upshifts for seamless acceleration.

While top speed hovers around 115–120 km/h (71–75 mph), the RS4 excels in corners. The lack of vibration (thanks to a balancer shaft) and Euro 3/4 compliance make it a refined, eco-friendly choice compared to smokey 2-strokes.

Handling and Dynamics: Pocket-Sized Precision

Chassis & Suspension:
The aluminum perimeter frame and asymmetric swingarm are borrowed from Aprilia’s GP racing tech. Paired with a 41 mm upside-down fork (110 mm travel) and preload-adjustable monoshock (130 mm rear travel), the RS4 tackles corners with surgical precision. The suspension is firm yet compliant, absorbing bumps without wallowing mid-corner.

Brakes & Wheels:
- Front: 300 mm disc with radial 4-piston caliper (Brembo-derived)
- Rear: 218 mm disc with single-piston caliper
- Tires: 110/80-17 (front) and 130/70-17 (rear)

The radial front brake delivers bite worthy of larger bikes, while the Michelin or Pirelli tires offer ample grip for aggressive leans. At 1350 mm (53.1 inches), the wheelbase strikes a balance between stability and flickability.

On the Road (and Track):
Riding the RS4 feels like piloting a bicycle with a jet engine. The low weight and narrow profile encourage knee-down antics, yet the riding position isn’t punishing for daily use. On track, keeping the engine above 9,000 RPM is key—the narrow powerband rewards disciplined gear changes.

Competition: How the RS4 Stacks Up

The RS4 125 Replica faced stiff competition from:

1. Yamaha YZF-R125:
2. Similar 15 HP, 125cc liquid-cooled engine.
3. Slightly more refined midrange but softer suspension.

4. Higher price tag and less aggressive styling.

5. Honda CBR125R:

6. Budget-friendly, ultra-reliable.

7. Underpowered (13 HP) and less engaging chassis.

8. KTM RC 125:

9. 15 HP, WP suspension, and sharp design.
10. Pricier and less established aftermarket support.

Why the RS4 Wins:
Aprilia’s race-bred chassis and premium components (upside-down forks, radial brakes) give it an edge for spirited riding. While the Yamaha and KTM match its power, the RS4’s design and handling pedigree make it the most "superbike-like" in the segment.

Maintenance: Keeping the RS4 Razor-Sharp

The 4-stroke engine is low-maintenance compared to 2-strokes, but adherence to service intervals is crucial:

Key Maintenance Tips:
1. Oil Changes: Every 5,000 km (3,100 miles) with SAE 5W-40 oil. Capacity: 1.2 liters (with filter).
2. Valve Adjustments: Check every 10,000 km (6,200 miles)—a DIY task with basic tools.
3. Chain Care: Clean and lubricate every 500 km (310 miles). Stock chain: 136 links, 17/40 sprockets.
4. Coolant: Replace every 2 years (780 ml capacity).
5. Brake Fluid: DOT 4, changed biannually.

Upgrades from MOTOPARTS.store:
- High-performance air filters for sharper throttle response.
- Adjustable levers for personalized control.
- Aftermarket exhausts (check local regulations) to shed weight and enhance sound.

Conclusion: The Ultimate Learner’s Bike

The Aprilia RS4 125 Replica isn’t just a stepping stone—it’s a motorcycle that teaches you to ride like a pro. Its combination of superbike styling, track-ready dynamics, and bulletproof 4-stroke reliability makes it a standout in the 125cc class. While seasoned riders might crave more power, newcomers will appreciate its forgiving nature and the skills it hones.

Whether carving canyon roads or navigating urban sprawl, the RS4 125 Replica proves that big thrills come in small packages. And with MOTOPARTS.store’s extensive catalog, personalizing this Italian gem has never been easier.

Specifications sheet