🏷️ Basic Information

Make:

Yamaha

Model:

YZ250

Year:

2008

Vehicle Type:

Motocross Motorcycle

Engine Type:

2-Stroke

👋 Introduction

Positioning:

The Yamaha YZ250 has long been a benchmark in the open-class 2-stroke motocross segment, known for its powerful engine and agile handling. This manual caters to owners and mechanics dedicated to maintaining and optimizing this performance machine.

Competitors:

Primarily competes with other 250cc 2-stroke motocross bikes from brands like KTM (250 SX) and Honda (CR250R, though discontinued in later years, it was a key competitor during this era).

Vehicle Highlights:

Renowned for its torquey 2-stroke powerband, nimble chassis, and long-travel suspension, the 2008 YZ250 offered a raw, engaging riding experience favored by many motocross enthusiasts.

Value:

This manual is essential for any owner looking to perform in-depth maintenance, troubleshooting, and repairs to keep their 2008 YZ250 running at peak performance, saving on dealership costs.

📋 Manual Details

Main Coverage:

Comprehensive service, repair, and workshop procedures for the 2008 Yamaha YZ250.

Specific Systems Covered:

Engine, transmission, chassis, suspension (front and rear), brakes (front and rear), electrical system, fuel system, cooling system, lubrication system, exhaust system, bodywork, and troubleshooting.

Estimated Pages:

Extensive (typical for a full service manual, often 300+ pages)

Type:

Service Repair Workshop Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine Mechanical:

Detailed disassembly, inspection, assembly, and adjustment of all engine components including cylinder, piston, crankshaft, connecting rod, bearings, seals, and gaskets.

Carburetor:

Comprehensive information on Mikuni TMX carburetor removal, disassembly, cleaning, inspection, adjustment, and reassembly, including jetting recommendations.

Ignition System:

Details on CDI unit, ignition coil, spark plug, and wiring diagrams related to ignition timing and operation.

Clutch:

Service and adjustment procedures for the wet multi-plate clutch, including fiber plates, steel plates, springs, and clutch cover.

Transmission:

Complete breakdown and reassembly instructions for the 5-speed constant mesh gearbox, including gear inspection, shift drum, shift forks, and bearings.

Suspension Front:

Detailed service procedures for the Kayaba (KYB) Speed Sensitive System (SSS) inverted front forks, including oil change, seal replacement, fork spring service, and compression/rebound adjustment.

Suspension Rear:

Comprehensive service for the Monoshock rear suspension, including shock absorber disassembly, damping adjustments, spring preload, and linkage bearing maintenance.

Brakes Front:

Hydraulic disc brake system service, including caliper disassembly, pad replacement, master cylinder service, fluid flushing, bleeding, and rotor inspection.

Brakes Rear:

Hydraulic disc brake system service for the rear, including caliper, master cylinder, pad replacement, fluid management, and rotor inspection.

Electrical System:

Wiring diagrams, troubleshooting for lighting, ignition, and sensors, component testing, and battery maintenance.

Fuel System:

Fuel tank removal, petcock service, fuel line inspection, and carburetor fuel delivery.

Cooling System:

Not applicable for this 2-stroke model (air-cooled).

Lubrication System:

2-stroke oil injection system details (if applicable) or pre-mix ratio recommendations, gearbox oil specification and change intervals.

Exhaust System:

Removal, inspection, and reinstallation of the expansion chamber and silencer.

Bodywork Frame:

Fairing and plastic component removal/installation, frame inspection, and handlebar/control lever adjustments.

Routine Maintenance:

Step-by-step guides for oil changes, filter cleaning/replacement, spark plug replacement, chain adjustment, and general inspection.

Troubleshooting:

Diagnostic procedures for common issues, fault finding charts, and solutions for performance problems.

Engine Rebuild:

Detailed instructions for complete engine disassembly, inspection of critical components, and reassembly with proper torque specifications.

Suspension Service:

Complete guide to fork and shock absorber servicing, including fluid types, quantities, and seal replacement techniques.

Brake Overhaul:

Procedures for bleeding brake systems, caliper overhaul, and master cylinder servicing.

Electrical Diagnosis:

Troubleshooting guides for electrical faults using wiring diagrams and multimeter testing.

Depth:

Expert level, covering full mechanical overhauls, advanced diagnostics, and specific performance tuning insights.

Diagrams Illustrations:

Richly illustrated with clear, step-by-step diagrams and photographs for all procedures.

Torque Specifications:

Includes all essential torque values for critical fasteners throughout the motorcycle.

Clearances Tolerances:

Provides specific internal clearances and wear tolerances for engine components.

📊 Manual Specifications

Format:

PDF

Searchable Text:

Yes (typically)

Quality:

High resolution, optimized for clear viewing of diagrams.

Type:

Not Applicable (Digital Download)

Type:

Not Applicable (Digital Download)

⚙️ Engine Specifications

Engine Code:

Likely 5CU (check VIN for exact match)

Displacement:

249 cc

Bore X Stroke:

66.4 mm x 72.0 mm

Compression Ratio:

8.2:1 (Static)

Cooling Method:

Liquid-cooled

Ignition System:

Digital CDI (Capacitor Discharge Ignition)

Lubrication:

2-stroke pre-mix or oil injection (manual covers details)

Horsepower Estimate:

~45-50 hp (at crankshaft, estimated for the era)

Torque Estimate:

~30-33 lb-ft (at crankshaft, estimated for the era)

Carburetor Model:

Mikuni TMX38 (38mm) flat slide carburetor

Fuel Type:

Unleaded gasoline, minimum 91 octane recommended

Fuel Capacity:

8.0 L (2.1 US gal)

🔧 Transmission

Type:

5-speed constant mesh

Clutch Type:

Wet, multi-plate

Final Drive:

Chain drive

Gear Ratios:

Refer to manual for specific gear ratios (1st-5th).

Transmission Oil:

Yamalube 10W-40 API SG or equivalent (refer to manual for exact spec)

Transmission Oil Capacity:

Approximately 0.85 L (0.9 US qt)

📐 Dimensions

Length:

2185 mm (86.0 in)

Width:

825 mm (32.5 in)

Height:

1285 mm (50.6 in)

Wheelbase:

1475 mm (58.1 in)

Ground Clearance:

350 mm (13.8 in)

Seat Height:

995 mm (39.2 in)

Dry Weight:

97 kg (213.8 lbs)

Wet Weight:

Approximately 107 kg (235.9 lbs) (with all fluids)

Front Tire:

80/100-21 51M

Rear Tire:

110/90-19 62M

Wheel Type:

Spoked, Aluminum Rims

🛡️ Safety Features

Crash Test Rating:

Not Applicable (Off-road vehicle)

Braking System:

Hydraulic dual-piston front caliper with 250mm disc; Hydraulic single-piston rear caliper with 245mm disc.

Suspension Features:

Fully adjustable front and rear suspension for optimal handling and rider control.

Frame Construction:

Lightweight aluminum alloy frame designed for rigidity and handling.

Ergonomics:

Designed for rider comfort and control during aggressive riding.

💡 Technology Features

Features:

Not applicable (pure performance motocross motorcycle).

Features:

Not applicable.

Features:

Not applicable.

🔧 Maintenance

Engine Oil Change:

Every 15-20 hours of riding, or annually. Refer to manual for specific conditions.

Air Filter Cleaning:

After every few rides, or more frequently in dusty conditions. Manual details specific cleaning and oiling procedures.

Spark Plug Check Replace:

Check every 10 hours, replace as needed based on condition. Manual specifies correct plug type and gap.

Chain Tension Adjustment:

Check before every ride, adjust as needed. Manual provides correct slack specification.

Fork Oil Change:

Recommended every 20-30 hours of riding or annually, especially after hard use. Manual specifies oil type and level.

Brake Fluid Flush Bleed:

Recommended annually or if brake performance degrades. Manual details correct fluid and procedure.

Engine Oil Type:

Fully synthetic 2-stroke engine oil, specific grade recommended in manual (e.g., Yamalube 2R).

Transmission Oil Type:

Yamalube 10W-40 API SG or equivalent (manual for exact spec).

Coolant Type:

50/50 mix of distilled water and permanent antifreeze (ethylene glycol based, manual for specific type/color).

Brake Fluid Type:

DOT 4 Hydraulic Brake Fluid (manual for confirmation).

Common Wear Items:

Piston rings, clutch plates, wheel bearings, steering head bearings, linkage bearings, and fork seals are common wear items due to the nature of motocross riding.

Power Valve Maintenance:

The power valve system requires periodic cleaning and inspection for carbon buildup to ensure optimal performance.

Carburetor Jetting:

Proper carburetor jetting is crucial for performance and longevity; the manual provides baseline settings and guidance for adjustments based on altitude and temperature.

📚 Vehicle History

Yamaha Legacy:

Yamaha has a long and storied history in motocross, dating back to the legendary DT series and building a reputation for durable, high-performance off-road machines.

Yz250 Development:

The YZ250 has undergone continuous development, with significant updates in the late 1990s and early 2000s, including aluminum frames and improved suspension. The 2008 model represents a mature and refined iteration of this iconic platform.

Production Era:

YZ250 has been in continuous production since the 1970s, with the 2008 model being part of the modern aluminum frame generation.

🏆 Awards & Recognition

Model Accolades:

The YZ250 platform has consistently received praise from motocross publications for its enduring performance and rider-friendly character, often being lauded as a top choice in the 2-stroke class.