🏷️ Basic Information

Make:

Yamaha

Model:

YZ125

Model Year:

1995

Vehicle Type:

Motocross Motorcycle

Engine Configuration:

Single-cylinder, 2-stroke

Primary Market:

Off-road, Competition Motocross

👋 Introduction

Target Audience:

Yamaha YZ125 owners, motocross racers, mechanics, and enthusiasts seeking in-depth knowledge for maintenance and repair

Competitive Context:

The YZ125 was a key player in the 125cc motocross class, known for its potent 2-stroke engine and agility. This manual provides the essential information to keep this performance machine running optimally.

Unique Selling Points:

Factory-sourced information guarantees accuracy and completeness for the specific model year. Covers all aspects from basic checks to full engine rebuilds.

Value Proposition:

Cost-effective alternative to dealership service, empowering owners to perform maintenance and repairs, saving time and money.

📋 Manual Details

Manual Title:

1995 Yamaha YZ125 Service Manual

Coverage Scope:

Complete tear down and rebuild, maintenance, troubleshooting, repairs, technical specifications

Specific Sections Covered:

Engine, transmission, chassis, suspension, electrical system, fuel system, cooling system, lubrication, bodywork, troubleshooting guide, torque specifications, part diagrams

Page Count:

269 pages

Manual Type:

Factory Repair Manual / Service Manual

Language:

English

Format:

Digital Download (PDF assumed)

📖 Manual Coverage

Engine System:

Complete internal engine components, piston, rings, connecting rod, crankshaft, cylinder, cylinder head, reed valve assembly, power valve system, carburetor tuning and overhaul

Transmission System:

Gearbox components, clutch assembly, shift mechanism, gear ratios, clutch operation and service

Chassis And Suspension:

Frame components, front fork (telescopic), rear shock absorber (monoshock), swingarm, linkages, wheel bearings, steering head bearings, suspension adjustments and servicing

Electrical System:

Ignition system (CDI), lighting (if applicable for specific model variant), wiring diagrams, spark plug specifications, battery maintenance (if electric start equipped, unlikely for YZ125 of this era)

Fuel System:

Fuel tank, fuel lines, fuel filter, carburetor model (e.g., Mikuni VM), carburetor cleaning and adjustment, fuel mixture settings

Cooling Lubrication:

2-stroke pre-mix lubrication, gearbox oil specifications and change intervals, coolant for radiators (if liquid-cooled, which the YZ125 is)

Brake System:

Front and rear hydraulic disc brakes, brake fluid specifications, bleeding procedures, pad replacement, caliper servicing

Wheel Tire System:

Wheel assembly, spokes, rim specifications, tire sizes, tire pressure recommendations, wheel balancing

Major Repair Procedures:

Complete engine rebuild (top-end and bottom-end), transmission overhaul, suspension fork and shock absorber rebuild, clutch replacement, brake caliper overhaul

Routine Maintenance:

Oil changes (gearbox), spark plug inspection and replacement, air filter cleaning and oiling, chain adjustment and lubrication, coolant checks, brake system checks, suspension adjustments

Troubleshooting Diagnostics:

Diagnosis of common running issues, ignition system faults, carburetor problems, clutch slippage, suspension performance issues

Electrical Diagnostics:

Testing of ignition components, wiring continuity checks, troubleshooting electrical faults using wiring diagrams

Special Tools And Jigs:

Identification of specific tools required for disassembly, assembly, and adjustments (e.g., flywheel puller, clutch holding tool)

Depth Of Coverage:

Comprehensive, covering full workshop-level repair and maintenance procedures suitable for experienced mechanics and dedicated enthusiasts

Detail Level:

High-detail with step-by-step instructions, detailed illustrations, and diagrams for complex procedures

Diagnostic Capabilities:

Includes detailed troubleshooting charts and guides to diagnose performance issues and component failures

📊 Manual Specifications

File Format:

PDF (Portable Document Format) - commonly used for digital service manuals

Searchability:

Likely text-searchable if digitally produced from original scans or factory files

Print Quality:

Dependent on source scan, but typically high-resolution for clarity of diagrams and text

Binding Type:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Engine Type:

Liquid-cooled, 2-stroke, single cylinder

Bore X Stroke:

56.0 mm x 50.7 mm (Typical for this generation YZ125)

Displacement:

123cc (Approximate)

Compression Ratio:

8.4:1 (Typical, may vary slightly by spec revision)

Reed Valve:

Yamaha Power Valve System (YPVS) for improved powerband

Horsepower:

Approximately 35-38 HP (at crankshaft, typical for 125cc class of the era)

Torque:

Not typically quoted in HP, but significant for its displacement

Carburetor:

Mikuni VM28SS (Typical for this model)

Fuel Type:

Unleaded gasoline, minimum 91 octane recommended

Fuel Mixture:

2-stroke oil mixed with gasoline (e.g., 20:1 or 32:1 ratio depending on oil and usage - manual will specify)

🔧 Transmission

Transmission Type:

6-speed constant mesh

Clutch Type:

Wet, multi-plate

Final Drive:

Chain drive

Gear Ratios:

Specific ratios will be detailed in the manual (e.g., 1st gear: 2.500, 2nd: 1.818, etc.)

📐 Dimensions

Overall Length:

Approx. 2170 mm (85.4 in)

Overall Width:

Approx. 820 mm (32.3 in)

Overall Height:

Approx. 1275 mm (50.2 in)

Dry Weight:

Approx. 95 kg (209 lbs)

Fuel Tank Capacity:

Approx. 8.0 liters (2.1 US gal)

Wheelbase:

Approx. 1455 mm (57.3 in)

🛡️ Safety Features

Safety Certification:

Not applicable for off-road competition vehicles in the same way as street-legal vehicles

Braking System:

Hydraulic disc brakes front and rear for responsive stopping power

Suspension Performance:

Adjustable front forks (e.g., KYB or Showa) and rear monoshock with adjustable damping and preload for optimal control and stability

Frame Construction:

Strong steel or aluminum frame designed for durability and handling under extreme motocross conditions

💡 Technology Features

Infotainment System:

Not applicable - this is a purebred competition motocross bike with no infotainment features.

Rider Aids:

Not applicable - the focus is on rider skill and mechanical feedback. No electronic rider aids.

Connectivity Features:

Not applicable. The bike is designed for off-road performance without any electronic connectivity.

Power Valve System:

Yamaha Power Valve System (YPVS) for improved torque at low RPM and broader powerband.

🔧 Maintenance

Engine Top End Service:

Recommended every 20-40 hours of racing/hard use (piston, rings, cylinder inspection). Manual will provide precise intervals.

Clutch Inspection:

Regular inspection for wear, lubrication, and proper operation. Clutch plate replacement typically at 50-100 hours depending on usage.

Gearbox Oil Change:

Every 15-20 hours of use or annually. Manual will specify exact interval and oil type.

Air Filter Cleaning:

After every ride in dusty conditions, or at least every few rides. Manual will detail cleaning and oiling procedure.

Chain Cleaning Lubrication:

After every ride, or as needed. Manual will specify lubricant type and adjustment procedure.

Gearbox Oil:

Yamalube Gear Oil 10W-30 or equivalent API GL-4 (Manual will confirm specific viscosity and API rating).

Coolant:

Mixture of distilled water and a high-quality motorcycle antifreeze/coolant (e.g., ethylene glycol based) at a 50/50 ratio. Manual will specify.

Brake Fluid:

DOT 3 or DOT 4 brake fluid (Manual will specify exact type for Yamaha hydraulic systems).

2 Stroke Oil:

High-quality 2-stroke motorcycle oil, specifically for competition or performance engines. Manual will recommend specific grades and mixing ratios.

Common Wear Items:

Clutch plates, piston rings, wheel bearings, steering head bearings, chain and sprockets are common wear items on high-performance motocross bikes.

Power Valve Maintenance:

Yamaha's YPVS system requires regular cleaning and lubrication to ensure smooth operation and optimal power delivery. Carbon buildup can be an issue.

Carburetor Tuning:

Proper carburetor jetting and adjustment are critical for performance and can require fine-tuning based on altitude, temperature, and humidity. The manual covers this in detail.

📚 Vehicle History

Yamaha Motorsport Legacy:

Yamaha has a long and storied history in motorcycle racing, particularly in motocross, with the YZ line being a cornerstone of their off-road performance division.

Yz125 Development:

The YZ125 has undergone continuous development since its inception, with each model year introducing improvements in engine performance, suspension technology, and chassis design. The 1995 model represents a refinement of the preceding generations.

Production Period:

The YZ125 has been in continuous production for many decades, with the 1995 model being part of the evolution of this popular competition bike.

🏆 Awards & Recognition

Motocross Class Competitiveness:

The YZ125, throughout its generations including the 1995 model, was a highly competitive machine in its class, often earning praise for its engine power and handling characteristics in period reviews and championships.