🏷️ Basic Information

Make:

Aprilia

Model:

RS125

Model Variants:

Rotax 122, Rotax 123 (specific variants depend on exact model year covered by manual)

Engine Code:

Rotax 122 (2-stroke, liquid-cooled), Rotax 123 (2-stroke, liquid-cooled)

👋 Introduction

Market Position:

The Aprilia RS125 has historically occupied a premium segment in the 125cc sportbike category, known for its performance, handling, and race-inspired styling, often appealing to younger riders and those seeking a track-day capable machine.

Competitive Analysis:

Competed with other European and Japanese 125cc two-stroke sportbikes like the Yamaha TZR125, Honda NSR125, and Cagiva Mito 125. Its strong performance often set it apart.

Key Features:

High-revving Rotax two-stroke engine, sophisticated chassis dynamics, aggressive sportbike ergonomics, premium suspension components (often adjustable), and racing-derived aesthetics.

📋 Manual Details

Coverage Areas:

Comprehensive mechanical, electrical, and bodywork systems for the Aprilia RS125

Page Count:

Estimating between 300-500 pages based on typical 'Deluxe' service manual coverage.

Manual Type:

Service Repair Manual

Language:

English

Format:

PDF

📖 Manual Coverage

Engine:

Full engine disassembly, assembly, tuning, and troubleshooting for Rotax 2-stroke engines, including top-end (cylinder, piston, rings), bottom-end (crankshaft, bearings), carburetion, exhaust system, and cooling system.

Transmission:

Clutch operation, gearbox disassembly and assembly, gear selection mechanism, lubrication, and common issues.

Fuel System:

Carburetor identification (e.g., Dell'Orto PHBH, VHST), jetting specifications, float bowl adjustment, fuel lines, fuel pump (if applicable), and fuel tank maintenance.

Electrical System:

Ignition system (CDI, stator, spark plug), lighting circuits (headlight, taillight, indicators), charging system (alternator, rectifier/regulator), starter motor, battery maintenance, wiring diagrams, and fuse box layout.

Brakes:

Front and rear brake systems (disc brakes), caliper maintenance, master cylinder overhaul, brake fluid specifications and bleeding procedures, pad replacement, and rotor inspection.

Suspension:

Front fork (e.g., Marzocchi, Paioli) disassembly, seal replacement, oil type and level specifications, rear shock absorber adjustment and maintenance, linkage lubrication.

Cooling System:

Radiator inspection and cleaning, coolant type and capacity, water pump maintenance, thermostat operation, and troubleshooting overheating issues.

Chassis And Frame:

Frame inspection, steering head bearing maintenance, swingarm lubrication, wheel bearing replacement, and general chassis geometry checks.

Bodywork And Fairings:

Fairing removal and installation, seat removal, tank cover maintenance, and aesthetic component care.

Preventative Maintenance:

Oil changes, filter replacements (air, oil if applicable), chain adjustment and lubrication, spark plug inspection/replacement, coolant flushes, and brake fluid changes.

Troubleshooting:

Step-by-step diagnostic guides for common starting problems, engine misfires, electrical faults, brake issues, and suspension performance problems.

Repair Procedures:

Detailed instructions for component replacement, major overhauls, seal replacements, bearing changes, and more.

Technical Specifications:

Torque values for critical fasteners, engine timing specifications, valve clearances (if applicable, though unlikely for a 2-stroke), fluid capacities, and electrical resistance values.

Technical Depth:

In-depth, professional-level technical information suitable for experienced mechanics and dedicated DIY enthusiasts, covering everything from basic maintenance to complete engine rebuilds and electrical system diagnostics.

📊 Manual Specifications

File Format:

PDF (Portable Document Format)

Print Quality:

High resolution, ensuring clear and legible text and diagrams when printed. Optimized for clarity.

Binding Type:

N/A (Digital PDF format)

Paper Type:

N/A (Digital PDF format)

⚙️ Engine Specifications

Engine Type:

Liquid-cooled, 2-stroke, single-cylinder

Bore X Stroke:

Typically 54 mm x 54.5 mm (Rotax 122/123 variants)

Displacement:

124.8 cc

Compression Ratio:

Varies by specific model year, often around 12.5:1

Horsepower:

Typically in the range of 30-35 HP (may vary based on regional restrictions and specific model year).

Torque:

Approximately 20-22 Nm at 8,000-9,000 RPM (estimate based on typical power output).

Carburetor:

Dell'Orto PHBH 28 or VHST 28 (common; manual will detail specific model and settings)

Fuel Type:

Unleaded gasoline (minimum octane rating specified in manual, typically 95 RON)

Ignition Type:

Electronic ignition (CDI) with variable timing.

Lubrication System:

Two-stroke oil injection system (separate oil reservoir) or pre-mix (manual will specify).

🔧 Transmission

Transmission Type:

6-speed constant mesh sequential gearbox

Clutch:

Hydraulically operated, multi-plate wet clutch

Final Drive:

Chain driven

📐 Dimensions

Length:

Approx. 1940-2010 mm (varies by model year)

Width:

Approx. 720-770 mm (varies by model year)

Height:

Approx. 1060-1110 mm (seat height varies)

Dry Weight:

Approx. 130-140 kg (varies by model year and specific components)

Fuel Tank Capacity:

Approx. 13-14 liters

🛡️ Safety Features

Safety Ratings:

N/A (Motorcycles are not typically rated by agencies like NHTSA in the same way as cars).

Braking System:

Front: Single disc with 4-piston caliper; Rear: Single disc with 2-piston caliper. ABS not standard on most RS125 models.

Lighting:

Halogen headlight, LED taillight, standard incandescent turn signals.

Chassis Design:

Sturdy perimeter frame for rigidity and predictable handling.

💡 Technology Features

Infotainment System:

N/A (Analog instrumentation with tachometer, speedometer, odometer, fuel gauge, and indicator lights.)

Driver Assistance:

N/A (No electronic rider aids like traction control or advanced ABS are typically present on this model).

🔧 Maintenance

Oil Change Interval:

Engine oil change for gearbox (if applicable) typically every 5,000-6,000 km or annually. 2-stroke oil reservoir refill as needed.

Spark Plug Replacement:

Recommended inspection every 3,000-4,000 km, replacement as needed based on condition. Specific plug type and gap in manual.

Air Filter Cleaning Replacement:

Clean/replace air filter every 6,000-8,000 km or more frequently in dusty conditions.

Chain Maintenance:

Lubricate and adjust chain every 500-1,000 km, check for wear and tension.

Coolant Flush:

Flush and replace coolant every 2 years or as specified by manufacturer.

Engine Oil Type:

For gearbox lubrication: API GL-4 or GL-5, SAE 75W/90 or 10W/40 motorcycle specific gear oil. For 2-stroke oil: High-quality fully synthetic 2-stroke racing oil.

Brake Fluid Type:

DOT 4 or DOT 5.1 brake fluid (verify with manual for specific model year).

Coolant Type:

Ethylene glycol-based antifreeze with corrosion inhibitors (typically a 50/50 mix with distilled water).

Fork Oil Type:

Specific suspension fluid (e.g., SAE 10W or 15W) with precise level specifications detailed in the manual.

Known Issues:

Common issues include wear on the powervalve (A.E.S.) mechanism, potential for carbon buildup in the exhaust and cylinder due to the 2-stroke nature, clutch wear, and sometimes electrical gremlins if not maintained. Overheating can occur if cooling system is neglected. Some models had issues with crankshaft seals.

📚 Vehicle History

Brand Heritage:

Aprilia has a long and successful history in motorcycle racing, particularly in smaller displacement categories (125cc and 250cc Grand Prix), which heavily influenced the design and performance of the RS125.

Model Evolution:

The RS125 has undergone several iterations and styling updates throughout its production run, often with minor engine enhancements and chassis improvements. Key generations often align with chassis redesigns and engine updates (e.g., introduction of Rotax 122 vs. earlier engines).

Production Years:

The Aprilia RS125 has been in production for an extended period, with significant generations produced from the early 1990s through to the late 2010s, eventually being phased out in favor of 4-stroke models.

Manufacturing Locations:

Primarily manufactured in Italy.

🏆 Awards & Recognition

Recognitions:

The RS125 has been widely praised in motorcycle reviews for its class-leading performance and handling, often winning comparison tests against its contemporaries. It has achieved iconic status among 125cc sportbikes.