🏷️ Basic Information

Make:

Yamaha

Model:

YZ250

Year:

2005

Vehicle Type:

Motocross Motorcycle

Product Code:

YZ250_2005_WSM_DL

👋 Introduction

Positioning:

The 2005 Yamaha YZ250 was a highly competitive machine in the premier 250cc two-stroke motocross class, known for its potent engine and agile handling.

Competitors:

Competed directly against models like the Honda CR250R, Kawasaki KX250, and Suzuki RM250.

Engine Type:

Liquid-cooled, 249cc, 2-stroke, Reed valve induction.

Suspension Type:

Upside-down telescopic front forks, Monoshock rear suspension (Monocross system).

Braking System:

Hydraulic disc brakes front and rear.

Frame Type:

Aluminum alloy frame.

📋 Manual Details

Engine Mechanical:

Yes

Engine Electrical:

Yes

Fuel System:

Yes

Exhaust System:

Yes

Transmission:

Yes

Clutch:

Yes

Cooling System:

Yes

Suspension Front:

Yes

Suspension Rear:

Yes

Brakes Front:

Yes

Brakes Rear:

Yes

Wheels Tires:

Yes

Frame Chassis:

Yes

Electrical System:

Yes

Bodywork Plastics:

Yes

Troubleshooting:

Yes

Estimated Pages:

Approx. 300-400 pages (typical for this era/type of manual)

Type:

Workshop Service Repair Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine Systems:

Top-end rebuild (cylinder, piston, rings), bottom-end rebuild (crankshaft, connecting rod, bearings), power valve system, carburetor overhaul and tuning, ignition system inspection, cooling system flush and maintenance.

Transmission Clutch:

Gearbox disassembly and reassembly, clutch pack replacement, clutch cable adjustment, primary drive inspection.

Suspension Brakes:

Fork seal replacement, fork oil change, shock absorber disassembly and reassembly, brake fluid flush, pad replacement, caliper inspection, master cylinder overhaul.

Electrical Chassis:

Wiring diagrams, lighting system checks, ignition coil testing, general chassis component inspection and tightening.

Routine Maintenance:

Oil changes, filter cleaning/replacement, chain adjustment and lubrication, spark plug inspection and replacement, air filter cleaning.

Repair Procedures:

Step-by-step instructions for all major component overhauls and replacements, including engine, transmission, suspension, and brakes.

Troubleshooting Diagnostics:

Systematic diagnosis of common problems, fault finding charts, symptom-based troubleshooting for engine performance issues.

Specifications Data:

Torque specifications for all fasteners, engine timing data, fluid capacities, wear limits, and tolerances.

Depth:

Comprehensive, covering everything from basic maintenance to complete engine and suspension rebuilds. Suitable for both home mechanics and professional technicians.

📊 Manual Specifications

Format:

PDF

Searchable Text:

Yes (typically for officially sourced PDFs)

Quality:

High-resolution, clear illustrations and text

Binding:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Engine Type:

Liquid-cooled, 2-stroke, single-cylinder

Displacement:

249 cc

Bore X Stroke:

66.4 mm x 72.0 mm

Compression Ratio:

8.2:1 (typically, check manual for exact)

Carburetor:

Keihin PWK38S, 38mm, with Power Jet

Ignition:

CDI

Starting System:

Kick starter

Horsepower:

Approx. 50-52 HP (at crankshaft, typical for class)

Torque:

Approx. 32-34 lb-ft (at crankshaft, typical for class)

Fuel Type:

Unleaded gasoline (91 octane or higher recommended)

Fuel Mixture:

2-stroke pre-mix oil (Yamalube 2R or equivalent recommended), 50:1 ratio (check manual for precise ratio)

Fuel Tank Capacity:

8.0 Liters (2.1 US gallons)

🔧 Transmission

Type:

5-speed constant mesh

Gear Ratios:

1st: 2.333 (35/15), 2nd: 1.750 (28/16), 3rd: 1.333 (24/18), 4th: 1.090 (24/22), 5th: 0.958 (23/24)

Primary Drive:

Gear

Final Drive:

Chain drive (520 O-ring)

Clutch:

Wet, multiple-disc, cable operated

Transmission Oil Type:

Yamaha Genuine Gear Oil (or equivalent SAE 80 API GL-4)

Transmission Oil Capacity:

1.0 Liter (1.1 US qt)

📐 Dimensions

Overall Length:

2170 mm (85.4 in)

Overall Width:

825 mm (32.5 in)

Overall Height:

1285 mm (50.6 in)

Seat Height:

990 mm (39.0 in)

Wheelbase:

1475 mm (58.1 in)

Ground Clearance:

350 mm (13.8 in)

Dry Weight:

98 kg (216 lbs)

Wet Weight:

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

🛡️ Safety Features

Safety Ratings:

N/A (Motorcycles typically do not receive NHTSA or Euro NCAP ratings)

Active Safety:

Excellent braking performance from hydraulic disc brakes, responsive handling, rider control aids.

Passive Safety:

Robust frame construction, reliable components. Rider protection relies on rider gear (helmet, body armor, etc.).

💡 Technology Features

Infotainment System:

N/A (Performance motocross motorcycle)

Driver Assistance:

N/A (Performance motocross motorcycle)

Connectivity Features:

N/A (Performance motocross motorcycle)

Power Valve System:

Yamaha Power Valve System (YPVS) for improved low-to-mid range power delivery and broader powerband.

Cooling System:

Advanced liquid cooling system for optimal engine temperature management.

🔧 Maintenance

Oil Change Interval:

Every 10-15 hours of riding (check manual for specific conditions).

Air Filter Cleaning:

After every few rides, or more frequently in dusty conditions (check manual).

Chain Maintenance:

Lubricate and check tension every ride.

Spark Plug Inspection:

Every 20-30 hours of riding.

Top End Rebuild:

Recommended every 50-100 hours of riding, depending on riding style and maintenance.

Coolant:

Yamaha Anti-Rust Super Coolant or equivalent ethylene glycol-based coolant with distilled water (50:50 mix).

Brake Fluid:

DOT 4 Hydraulic Brake Fluid

Fork Oil:

Yamaha Suspension Oil (e.g., SAE 0W-30 or SAE 10W, check manual for specific type and level)

Common Wear Items:

Piston rings, clutch plates, wheel bearings, steering head bearings, chain and sprockets, spark plug, air filter, fork seals.

Potential Problems:

Power valve sticking due to carbon buildup, carburetor jetting sensitivity to altitude and temperature, occasional crank seal leaks.

📚 Vehicle History

Heritage:

Yamaha has a long and successful history in off-road and motocross racing, with the YZ line being a cornerstone of their performance motorcycle division since the 1970s.

Evolution Yz250:

The YZ250 has undergone continuous development, with significant updates including aluminum frames, revised suspension, and engine refinements leading up to and beyond the 2005 model year. The 2005 model represented a mature and highly refined iteration of the two-stroke YZ250 platform.

Production Era:

The YZ250 platform has been in continuous production for decades, with the 2005 model being part of the generation that transitioned to aluminum frames and advanced suspension technology.

🏆 Awards & Recognition

Motocross Awards:

The YZ250 consistently received praise and awards from motocross publications for its performance, handling, and race-winning capabilities throughout its production run.

Performance Ratings:

Highly rated by motorcycle journalists and racers for its powerful two-stroke engine and sharp handling characteristics.

Certifications:

N/A (Motorcycles are not typically certified in the same way as road vehicles for safety features).