Segment:
Performance motocross motorcycle, highly competitive 250cc four-stroke class.
Key Competitors 2009:
Honda CRF250R, Kawasaki KX250F, Suzuki RM-Z250, KTM 250 SX-F.
Engine Type:
Liquid-cooled, DOHC, four-valve, four-stroke single-cylinder.
Fuel Delivery:
Keihin Electronic Fuel Injection (EFI) system.
Suspension Front:
Inverted telescopic fork (e.g., KYB Speed Sensitive System - SSS).
Suspension Rear:
Monocross with adjustable linkage and KYB rear shock.
Frame Type:
Aluminum bilateral beam frame.
Systems Covered Summary:
Engine, chassis, electrical, maintenance, troubleshooting, and specifications for the Yamaha YZ250F.
Estimated Page Count:
Approximately 300-400 pages (typical for a comprehensive service manual of this era).
Type:
Service Repair Workshop Manual
Format:
Digital (likely PDF), potentially printable.
Engine Internal:
Top-end rebuild (cylinder, piston, rings, valves), bottom-end rebuild (crankshaft, connecting rod, bearings), lubrication system, cooling system, fuel injection system, ignition system.
Powertrain:
Transmission (gearbox internals, clutch operation, shift drum and forks), final drive (chain and sprockets).
Chassis Suspension:
Front fork (disassembly, assembly, oil levels, adjustments), rear shock absorber (overhaul, adjustments), swingarm, linkage system, steering head bearings.
Brakes:
Front and rear brake caliper service, master cylinder overhaul, brake fluid replacement, bleeding procedures, rotor inspection.
Electrical:
Wiring diagrams, troubleshooting electrical faults, lighting system, ignition system components, battery maintenance, starter system.
Fuel System:
Fuel pump, fuel injector cleaning and testing, fuel filter replacement, fuel tank maintenance.
Routine Maintenance:
Oil changes, filter replacements (oil, air), spark plug replacement, chain lubrication and adjustment, valve clearance checks and adjustment.
Troubleshooting:
Diagnosis of common performance issues, starting problems, unusual noises, electrical system faults.
Disassembly Assembly:
Step-by-step instructions for major component removal, installation, and overhaul.
Special Tools:
Identification and usage of specialized tools required for specific repairs and adjustments.
Depth:
Comprehensive coverage from basic maintenance to complete engine and transmission rebuilds. Includes diagnostic procedures and detailed specifications.
Digital Format:
PDF (Portable Document Format)
Readability:
High-resolution scanned pages for clear text and diagrams. Searchable text functionality is highly probable for digital versions.
Binding:
Not applicable for digital format; if printed, typically bound for durability.
Paper Quality:
Not applicable for digital format; if printed, would typically be on sturdy, coated paper suitable for workshop environments.
Engine Configuration:
Single-cylinder, liquid-cooled, four-stroke, DOHC, four valves.
Bore X Stroke:
77.0 mm x 53.6 mm
Compression Ratio:
12.5:1 (typical for this model year)
Lubrication System:
Wet sump, integrated oil in crankcase and transmission.
Horsepower Estimated:
Approximately 35-40 HP at the crank (actual dyno results may vary).
Torque Estimated:
Approximately 20-23 lb-ft at the crank (actual dyno results may vary).
Fuel Induction:
Keihin 40mm throttle body with EFI (dual injectors typically).
Fuel Type:
Unleaded gasoline, minimum 91 octane (RON+MON)/2 / 87 AKI.
Transmission Type:
Constant mesh 5-speed sequential.
Clutch Type:
Wet, multiple-disc, cable-actuated.
Gear Ratios:
Specific ratios would be detailed in the manual (e.g., 1st: 2.333, 2nd: 1.750, 3rd: 1.381, 4th: 1.136, 5th: 0.917).
Transmission Oil Type:
Yamalube 4 (or equivalent API SG, SAE 10W-30 or 20W-40).
Transmission Oil Capacity:
Approximately 0.75 liters (check manual for exact fill).
Overall Length:
Approximately 2170 mm (85.4 in)
Overall Width:
Approximately 815 mm (32.1 in)
Overall Height:
Approximately 1270 mm (50.0 in)
Seat Height:
Approximately 990 mm (39.0 in)
Wheelbase:
Approximately 1475 mm (58.1 in)
Dry Weight:
Approximately 97 kg (213.8 lbs) - curb weight will be slightly higher.
Fuel Tank Capacity:
Approximately 8.0 liters (2.1 gal).
Ground Clearance:
Approximately 355 mm (14.0 in)
Front Tire Size:
80/100-21 51M (e.g., Dunlop Geomax MX51)
Rear Tire Size:
100/90-19 57M (e.g., Dunlop Geomax MX51)
Wheel Type:
Spoked aluminum rims.
Safety Certification:
N/A (Motocross bikes are not subject to the same road-legal safety standards as street vehicles).
Braking System:
Hydraulic disc brakes front and rear.
Throttle Control:
Standard throttle limiter (can be modified).
Handlebar Protection:
Often includes foam pad on crossbar for rider protection.
Infotainment System:
N/A (Motocross motorcycles do not feature infotainment systems).
Rider Aids:
N/A (No electronic rider aids such as ABS or traction control are present on this model).
Connectivity Features:
N/A (No connectivity features are present).
Efi System Type:
Advanced EFI system with dual injectors for optimal fuel atomization and power delivery across the rev range.
Engine Oil Change:
Recommended every 10-15 hours of operation, or as specified in the manual, depending on riding conditions.
Air Filter Cleaning:
Inspect and clean every 5 hours, depending on dust and conditions. Replace as needed.
Valve Clearance Check:
Recommended every 20-30 hours of operation, or as per manual recommendations for initial checks.
Spark Plug Replacement:
Check at 10-hour intervals, replace as needed or every 30-40 hours for optimal performance.
Engine Oil Spec:
Yamalube 4 (or equivalent API SG, SAE 10W-30 or 20W-40).
Coolant Type:
Permanent type antifreeze coolant (ethylene glycol based), mixed with distilled water (50:50 ratio).
Brake Fluid Type:
DOT 4 hydraulic brake fluid.
Common Wear Items:
Clutch plates, piston and rings, valve seats, wheel bearings, swingarm bushings, steering head bearings, fork seals.
Efi System Notes:
Potential for injector clogging or pump issues if fuel is not clean. Regular cleaning and checking of fuel filter is crucial.
Yamaha Legacy:
Yamaha has a long and successful history in motocross racing, renowned for innovation and performance.
Yz250F Development:
The YZ250F has been a staple in the 250cc four-stroke class, with continuous development in engine technology, chassis design, and suspension. The 2009 model benefited from advancements in EFI and chassis stiffness.
Manufacturing Location:
Primarily Japan.
Racing Success:
YZ250F models have achieved significant success in professional motocross and supercross championships worldwide.
