🏷️ Basic Information

Make:

Yamaha

Model:

YZ125

Year:

1997

Type:

Motorcycle

Oem Part Number Manual:

N/A (Digital Download)

👋 Introduction

Vehicle Segment:

Motocross Competition

Target Audience:

Enthusiasts, mechanics, tuners, and owners focused on performance and maintenance of a competitive off-road motorcycle.

Key Rivals 1997:

Honda CR125R, Kawasaki KX125, Suzuki RM125

Vehicle Highlights:

Renowned for its strong mid-range power, agile handling, and competitive performance in its class.

Manual Value Proposition:

Provides essential, detailed technical information for maintaining and repairing the 1997 YZ125 to optimal racing condition.

📋 Manual Details

Primary Coverage:

Comprehensive Service and Repair

Scope:

All mechanical, electrical, and bodywork aspects

Estimated Pages:

300+

Type:

Service Repair Workshop Manual

Language:

English

Format:

PDF Download

📖 Manual Coverage

Engine:

Top-end overhaul, bottom-end assembly, piston, rings, cylinder, crankshaft, connecting rod, seals, gaskets, cooling system (if applicable, though YZ125 is typically air-cooled for this era), lubrication.

Fuel System:

Carburetor disassembly, cleaning, adjustment, jetting, fuel tank, fuel lines, fuel filter.

Ignition System:

Spark plug, ignition coil, CDI unit, stator, timing adjustments.

Transmission:

Clutch operation and adjustment, gearbox disassembly and reassembly, gear selection, shifting mechanism, transmission oil specifications and change intervals.

Suspension:

Front fork (KYB USD) disassembly, service, oil type and level, seal replacement, rear shock absorber service, spring preload adjustment, damping adjustments.

Brakes:

Front and rear hydraulic disc brake system, caliper service, master cylinder service, brake pad replacement, brake fluid specifications and bleeding procedures.

Electrical System:

Wiring diagrams, lighting system, horn, battery maintenance, fuses, troubleshooting electrical faults.

Chassis And Frame:

Frame inspection, steering head bearing service, swingarm pivot bearing service, linkage maintenance.

Wheels And Tires:

Wheel bearing service, spoke tensioning, tire pressure recommendations, tire replacement.

Bodywork And Plastics:

Seat removal, fuel tank removal, side panels, front and rear fenders, handlebar and controls.

Maintenance:

Regular service checks, lubrication points, filter cleaning/replacement, chain adjustment, brake adjustments, fluid level checks.

Troubleshooting:

Diagnostic procedures for common running issues, electrical problems, starting difficulties.

Repair:

Step-by-step instructions for component disassembly, reassembly, and replacement of worn or damaged parts.

Rebuilds:

Detailed instructions for engine, transmission, and suspension component rebuilds.

Specifications:

Torque specifications for critical fasteners, clearances, fluid capacities, and timing data.

Level:

Professional Workshop Level

Diagnostics:

In-depth troubleshooting charts and diagnostic flowcharts.

Precision Work:

Details on precision measurements, tolerances, and adjustments critical for performance.

📊 Manual Specifications

Format:

PDF

Searchable:

Yes (Optimized for text search)

Printability:

Printable (High Resolution)

Image Resolution:

High-resolution illustrations and diagrams

Physical Equivalent:

Spiral-bound for lay-flat use (typical for workshop manuals)

Physical Equivalent:

Durable, gloss-coated paper (typical for workshop manuals)

⚙️ Engine Specifications

Engine Type:

Liquid-cooled, 2-stroke, reed valve induction

Bore X Stroke:

54.0 mm x 54.5 mm

Displacement:

124 cc

Compression Ratio:

8.4:1 (Nominal)

Carburetor:

Mikuni TM38SS (38mm Slide Valve)

Horsepower Estimated:

Approx. 30-35 HP (at crankshaft, depending on tuning)

Torque Estimated:

Approx. 17-19 lb-ft (at crankshaft, depending on tuning)

Fuel Type:

Unleaded gasoline (minimum 91 octane recommended)

Fuel Mixture:

2-stroke oil mixed with gasoline (ratio specified in manual, typically 32:1 or 40:1)

Fuel Tank Capacity:

7.0 Liters (1.85 US gallons)

🔧 Transmission

Type:

6-speed constant mesh

Clutch Type:

Wet, multiple-disc

Gear Ratios:

1st: 2.615 (34/13), 2nd: 1.933 (29/15), 3rd: 1.500 (27/18), 4th: 1.235 (21/17), 5th: 1.050 (21/20), 6th: 0.913 (21/23)

Final Drive:

Chain drive (49T rear sprocket, 13T front sprocket typically)

Transmission Oil Type:

Yamaha Yamalube Gear Oil (or equivalent SAE 80 hypoid gear oil)

Transmission Oil Capacity:

0.65 Liters (0.69 US quarts)

📐 Dimensions

Overall Length:

2170 mm (85.4 in)

Overall Width:

825 mm (32.5 in)

Overall Height:

1275 mm (50.2 in)

Seat Height:

970 mm (38.2 in)

Wheelbase:

1475 mm (58.1 in)

Dry Weight:

94 kg (207 lbs)

Wet Weight Estimated:

102 kg (225 lbs)

🛡️ Safety Features

Vehicle Type Design:

Competition Off-Road Motorcycle (Not intended for road use)

Braking System:

Hydraulic disc brakes front and rear for superior stopping power and modulation.

Suspension Performance:

Performance-tuned KYB front forks and Monocross rear suspension for stability and control over rough terrain.

Frame Construction:

Strong steel semi-double cradle frame providing rigidity and rider feedback.

💡 Technology Features

Features:

N/A (Pure competition motocross motorcycle)

Features:

N/A (Pure competition motocross motorcycle)

Features:

N/A (Pure competition motocross motorcycle)

🔧 Maintenance

Oil Change Transmission:

Every 10-15 hours of riding or annually

Air Filter Cleaning:

After every few rides, or as needed depending on conditions

Spark Plug Inspection:

Every 10-15 hours of riding

Chain Lubrication Adjustment:

Every 5-10 hours of riding

Engine Top End Rebuild:

Recommended every 30-50 hours of aggressive riding (piston, rings, small end bearing)

Fork Oil Type:

Yamaha Fork Oil G10 or SAE 5W (Refer to manual for exact type and quantity)

Brake Fluid Type:

DOT 3 or DOT 4 hydraulic brake fluid

Coolant Type:

Yamaha Coolant (or equivalent ethylene glycol based, 50/50 mix with distilled water)

Typical Wear Items:

Clutch plates, piston and rings, wheel bearings, steering head bearings, exhaust packing, carburetor jets/needles.

Performance Tips:

Regular cleaning of the power valve system and proper jetting for altitude and temperature are crucial for optimal performance.

📚 Vehicle History

Yamaha Motorsports:

Yamaha has a rich and extensive history in motorsports, particularly in motocross, with decades of racing success and technological development.

Yz Lineage:

The YZ series has been a cornerstone of Yamaha's motocross lineup, with continuous refinement and upgrades throughout the years. The 1997 model represents a significant iteration with advancements in suspension and engine performance.

Manufacturing Location:

Japan (Primarily)

Production Period:

The YZ125 has been in continuous production for many decades, with the 1997 model being part of the late 90s generation.

🏆 Awards & Recognition

Motocross Contributions:

The YZ125, in its various iterations, has consistently been a strong performer and a popular choice in the 125cc motocross class, contributing to Yamaha's extensive race wins and championship titles.