🏷️ Basic Information

Make:

Yamaha

Model:

YZ250

Year:

2002

Vehicle Type:

Motocross Motorcycle

Engine Code:

1LR

Chassis Code:

4SP

👋 Introduction

Segment:

High-performance open-class motocross motorcycle

Reputation:

Renowned for its powerful two-stroke engine, agile handling, and competitive edge in motocross racing.

Competitors 2002:

Honda CR250R, Kawasaki KX250, Suzuki RM250, KTM 250 SX

Engine Character:

Explosive powerband, strong mid-range torque, characteristic two-stroke 'hit'

Chassis Design:

Lightweight aluminum frame, advanced suspension for the era

Handling Dynamics:

Agile, responsive, designed for aggressive riding and cornering

📋 Manual Details

Coverage:

Complete Service, Repair, and Workshop

Estimated Pages:

300+

Type:

Service/Repair Workshop Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine Mechanical:

Top end rebuild, bottom end overhaul, cylinder inspection and repair, piston and ring replacement, crankshaft service, bearing replacement, valve clearance (if applicable, though YZ250 is 2-stroke), cooling system (if applicable)

Fuel System:

Carburetor disassembly, cleaning, adjustment, jetting, fuel pump (if applicable), fuel lines, fuel tank service

Ignition System:

CDI unit, spark plug replacement, ignition coil, wiring diagrams, timing adjustment

Exhaust System:

Exhaust pipe inspection, silencer maintenance, packing replacement

Transmission Drivetrain:

Clutch inspection, adjustment, and replacement, gearbox disassembly and reassembly, gear inspection, output shaft service, chain and sprocket maintenance

Suspension:

Front fork service (oil change, seal replacement, damper rod inspection), rear shock absorber service (oil change, seal replacement, spring adjustment), linkage lubrication and inspection

Brakes:

Front and rear brake caliper service, master cylinder overhaul, brake pad replacement, brake fluid flush and replacement, rotor inspection and replacement, brake line maintenance

Wheels Tires:

Wheel bearing inspection and replacement, spoke tightening, tire mounting and balancing, rim inspection

Electrical System:

Wiring diagrams, headlight, taillight, brake light operation, battery maintenance, fuse replacement, general electrical troubleshooting

Chassis Frame:

Frame inspection, steering head bearing service, swingarm bearing service, shock linkage lubrication

Bodywork Plastics:

Seat removal and installation, fuel tank removal and installation, fender inspection, radiator shroud maintenance

Maintenance:

Pre-ride inspections, periodic maintenance checks, lubrication points, filter cleaning/replacement

Troubleshooting:

Diagnostic charts for common running issues, starting problems, and performance degradation

Repair:

Detailed step-by-step instructions for component disassembly, repair, and reassembly

Adjustment:

Carburetor tuning, clutch cable adjustment, brake lever adjustment, suspension sag adjustment

Installation:

Component installation procedures, torque specifications for critical fasteners

Depth:

Comprehensive, covering everything from basic maintenance to complete engine and transmission overhauls, including diagnostics and specifications.

📊 Manual Specifications

File Type:

PDF

Searchability:

Text-searchable (if original scan quality is good)

Quality:

High-resolution scans with clear, legible text and diagrams

Binding:

N/A (Digital Download)

Paper:

N/A (Digital Download)

Completeness:

Full workshop manual, likely containing all chapters of the original factory manual.

⚙️ Engine Specifications

Engine Type:

2-stroke, single-cylinder, liquid-cooled

Displacement:

249cc

Bore X Stroke:

66.4 mm x 72.0 mm

Compression Ratio:

8.4:1 (nominal, may vary with decomp port)

Intake System:

Reed valve induction

Exhaust Port Design:

Power Valve System (YPVS - Yamaha Power Valve System)

Horsepower Estimated:

50+ HP (at crankshaft, approximate)

Torque Estimated:

35+ lb-ft (at crankshaft, approximate)

Carburetor Model:

Keihin PWK38 (or similar 38mm flat-slide)

Fuel Type:

Unleaded gasoline, 91-98 octane recommended

Fuel Mixture:

Pre-mix (2-stroke oil and gasoline), 40:1 or 50:1 ratio typically specified

Type:

Liquid-cooled

Coolant Capacity:

Approx. 0.7 Liters

Coolant Type:

Ethylene glycol-based antifreeze (50/50 mix with distilled water)

🔧 Transmission

Type:

5-speed constant mesh

Options:

N/A (Factory specification)

Clutch Type:

Wet, multi-disc, cable-operated

Final Drive:

Chain drive

Gear Ratios:

Specific ratios detailed in manual (e.g., 1st: 2.615, 2nd: 1.933, 3rd: 1.500, 4th: 1.235, 5th: 1.000)

Transmission Oil Type:

Yamalube 2R or equivalent high-performance 2-stroke oil (for fuel mix), Gear oil for gearbox (e.g., SAE 10W-30 or 80W-90)

Transmission Oil Capacity:

Approx. 0.7 Liters (Gearbox oil)

📐 Dimensions

Length:

Approx. 2170 mm

Width:

Approx. 815 mm

Height:

Approx. 1270 mm

Wheelbase:

Approx. 1475 mm

Ground Clearance:

Approx. 355 mm

Seat Height:

Approx. 975 mm

Dry Weight:

Approx. 98 kg (216 lbs)

Wet Weight:

Approx. 105 kg (231 lbs) (with all fluids)

Fuel Tank Capacity:

Approx. 8.0 Liters (2.1 US gal)

🛡️ Safety Features

Safety Features Motorcycle:

N/A (Motorcycle safety is inherent in design and rider skill; no standardized ratings like cars).

Braking System:

Hydraulic disc brakes front and rear

Suspension Control:

Adjustable front forks and rear shock absorber for rider preference and terrain adaptation.

Frame Construction:

Strong, lightweight aluminum frame designed for rigidity and impact absorption.

Ergonomics:

Designed for rider control and balance during aggressive riding maneuvers.

💡 Technology Features

Features:

N/A (Pure performance motocross machine, no infotainment features).

Features:

N/A (No electronic driver assistance systems).

Features:

N/A (No electronic connectivity features).

Ypvs:

Yamaha Power Valve System (YPVS) electronically controlled for optimized power delivery across the RPM range.

Ignition Type:

Digital CDI (Capacitor Discharge Ignition)

🔧 Maintenance

Oil Change Engine Gearbox:

After every few rides or as specified in the manual (typically dependent on riding hours/conditions).

Air Filter Cleaning:

After every ride or as needed based on dust conditions.

Spark Plug Inspection:

Regularly, typically every 10-20 hours of riding.

Suspension Service:

Fork oil change every 20-40 hours, full suspension service annually or as needed.

Top End Rebuild:

Typically every 40-80 hours of hard riding (piston, rings, small end bearing).

Clutch Inspection:

Regularly, adjust free play as needed.

Premix Oil:

Yamalube 2R, Motul 800 2T, Castrol TTS, or equivalent high-performance synthetic 2-stroke racing oil.

Gearbox Oil:

Yamaha Gear Oil 10W-30 or SAE 80W-90 GL-4 gear oil.

Coolant:

50% distilled water and 50% ethylene glycol-based antifreeze.

Brake Fluid:

DOT 3 or DOT 4 hydraulic brake fluid.

Common Wear Items:

Piston rings, clutch plates, wheel bearings, steering head bearings, exhaust packing, swingarm bushings.

Engine Performance Issues:

Carburetor jetting sensitivity to altitude/temperature, power valve sticking if not maintained, wear in the reed block.

Suspension Maintenance:

Regular fork seal and bushing replacement due to harsh riding conditions.

📚 Vehicle History

Heritage:

Yamaha has a long and successful history in motorcycle racing, particularly in motocross, with numerous championships and innovations.

Yz250 Lineage:

The YZ250 has been a dominant force in the 250cc motocross class for decades, evolving significantly in chassis and engine technology.

2002 Updates:

For 2002, the YZ250 featured refinements to the suspension (Kayaba components), revised engine tuning, and updated styling.

Manufacturing Location:

Japan

🏆 Awards & Recognition

Motocross Praise:

Consistently praised in reviews and by racers for its potent engine and competitive chassis throughout its production run.

Race Success:

The YZ250 platform has been a winning motorcycle in numerous professional and amateur motocross and supercross events.