Segment:
High-performance motocross motorcycle
Competitors:
Honda CRF450R, Kawasaki KX450F, Suzuki RM-Z450, KTM 450 SX-F
Bike Characteristics:
Known for its powerful engine, agile handling, and competitive motocross performance. The 2008 model was a significant evolution in Yamaha's YZ-F lineage.
General Coverage:
Complete service, repair, maintenance, and troubleshooting for the 2008 Yamaha YZ450F.
Specific Systems:
Engine, fuel system, cooling system, exhaust system, transmission, clutch, chassis, suspension (front and rear), brakes (front and rear), electrical system, ignition system, lubrication system, bodywork, wheels, tires.
Estimated Pages:
300-400 (estimated, typical for this type of manual)
Type:
Workshop Service Manual
Engine Mechanical:
Complete engine disassembly, assembly, overhaul, piston and cylinder inspection, valve clearance adjustment, timing procedures, crankshaft and connecting rod service.
Fuel System:
Carburetor disassembly, cleaning, inspection, adjustment, jetting specifications, fuel pump, fuel lines, fuel filter.
Cooling System:
Radiator inspection, coolant type and capacity, water pump service, thermostat replacement, hoses and connections.
Transmission Drivetrain:
Gearbox disassembly and reassembly, gear inspection, shift drum and forks service, clutch assembly inspection and replacement, clutch fluid specifications.
Suspension Steering:
Front fork disassembly, service, seal replacement, oil type and level, rear shock absorber service, linkage inspection and lubrication, steering bearing service.
Brakes:
Front and rear brake caliper service, pad replacement, rotor inspection, brake fluid type and bleeding procedures, master cylinder overhaul.
Electrical Ignition:
Stator and generator service, CDI unit testing, spark plug specifications, ignition timing, wiring diagrams, battery specifications, lighting system.
Routine Maintenance:
Oil change intervals and specifications, oil filter part numbers, air filter cleaning and replacement, spark plug replacement, chain maintenance and adjustment, general lubrication points.
Troubleshooting:
Diagnostic charts for common problems, symptom-based troubleshooting guides, electrical system diagnostics, engine performance issues.
Major Repairs:
Engine rebuild procedures, transmission overhaul, suspension rebuild, component replacement and adjustment for all major systems.
Depth:
Comprehensive, covering from basic maintenance to full engine and chassis rebuilds, including detailed torque specifications and clearances.
Type:
Four-stroke, liquid-cooled, DOHC, single-cylinder
Bore X Stroke:
95.0 mm x 63.1 mm
Compression Ratio:
12.3:1
Horsepower:
Approx. 53 hp (at crankshaft, estimated for the era)
Torque:
Approx. 35 lb-ft (at crankshaft, estimated for the era)
Carburetor:
Keihin FCR-MX39
Fuel Type:
Unleaded gasoline, minimum 91 octane
Oil Type:
Yamaha Genuine Yamalube 4 (10W-40) or equivalent API SG, JASO MA certified motorcycle oil
Oil Capacity With Filter Change:
1.10 L (1.16 US qt)
Oil Capacity Without Filter Change:
1.00 L (1.06 US qt)
Oil Capacity Engine Overhaul:
1.20 L (1.27 US qt)
Safety Features:
N/A (Designed for closed-course competition, not street legal or safety-rated in automotive terms)
Braking System:
Hydraulic dual front disc brakes, Hydraulic rear disc brake
Suspension Design:
Front: Upside-down telescopic fork; Rear: Swingarm, monoshock (Monocross system)
Frame Type:
Aluminum bilateral beam frame
Engine Oil Change:
Every 15 hours of riding or as per manual recommendations.
Air Filter Cleaning:
Every 5-10 hours of riding, or more frequently in dusty conditions.
Spark Plug Replacement:
Refer to manual for mileage/hour recommendations, typically based on inspection.
Valve Clearance Check:
Every 20-30 hours of riding or annually.
Coolant Type:
Yamaha Genuine Super Coolant (or equivalent ethylene glycol-based antifreeze with demineralized water, 50/50 mix)
Brake Fluid Type:
DOT 4 hydraulic brake fluid
Common Wear Items:
Clutch plates, brake pads, chain and sprockets, wheel bearings, fork seals, air filter. Engine top-end (piston, rings) wear is dependent on usage and maintenance.
Specific Concerns 2008:
While generally reliable, some owners reported occasional carburetor tuning sensitivity and the need for meticulous maintenance to keep peak performance.
Heritage:
Yamaha has a long and successful history in motocross racing, with the YZ and YZ-F lines being instrumental in their competitive dominance.
Yz F Development:
The YZ450F has consistently evolved with engine technology, chassis design, and suspension advancements, with the 2008 model representing a key development phase.
Manufacturing Country:
Japan
