Segment:
Competitive Motocross 250cc four-stroke class
Target Audience:
Motocross racers, off-road enthusiasts, mechanics, owners seeking to maintain and repair their YZ250F
Competitors:
Honda CRF250R, Kawasaki KX250F, Suzuki RM-Z250
Vehicle Advantage:
Renowned for its powerful engine and responsive handling in its era.
Manual Value:
Provides essential knowledge for in-depth maintenance and repair, saving on professional service costs.
Engine:
Complete engine overhaul, top-end rebuild (cylinder, piston, rings, valve train), bottom-end rebuild (crankshaft, connecting rod, bearings), timing, lubrication system
Fuel System:
Carburetor disassembly, cleaning, adjustment, jetting, fuel pump (if applicable), fuel lines
Ignition System:
CDI unit, spark plug, stator, troubleshooting ignition faults
Cooling System:
Radiator, hoses, coolant, water pump
Transmission:
Gearbox disassembly, inspection, assembly, clutch operation, shift mechanism
Chassis:
Frame inspection, suspension (front fork and rear shock absorber service, adjustments, rebuild), steering system, swingarm
Brakes:
Hydraulic brake system (front and rear calipers, master cylinders, brake lines, bleeding), brake pad replacement, rotor inspection
Electrical System:
Wiring diagrams, battery maintenance, lighting, switches, troubleshooting electrical issues
Wheels And Tires:
Wheel bearing replacement, spoke tensioning, tire fitting and removal
Bodywork:
Fairing removal and installation, seat, fuel tank, fender service
Maintenance:
Regular service intervals, oil changes, filter replacements, chain adjustment, lubrication points
Troubleshooting:
Systematic diagnostic procedures for common and uncommon problems, fault codes interpretation (if applicable)
Repair:
Step-by-step instructions for disassembly, component replacement, and reassembly of all major and minor vehicle systems
Diagnostics:
Methods for identifying causes of malfunctions, checking component specifications, and verifying proper operation
Technical Adjustments:
Carburetor tuning, suspension sag adjustment, valve clearance adjustment, clutch lever adjustment
Depth:
Comprehensive; covers everything from basic maintenance to complete engine and transmission rebuilds, including detailed troubleshooting
Detail Level:
Highly detailed with exploded diagrams, torque specifications, and OEM procedures
Type:
Four-stroke, liquid-cooled, DOHC, single-cylinder
Displacement:
250 cc (249 cm³)
Bore X Stroke:
77.0 mm x 53.6 mm
Compression Ratio:
12.5:1 (typical for this model)
Horsepower:
Approx. 40-45 HP (at crankshaft, highly dependent on tuning and condition)
Torque:
Not explicitly stated in product info, but significant for its class.
Carburetor:
Keihin FCR 37 (flat slide carburetor)
Fuel Type:
Unleaded gasoline, premium octane recommended
Fuel Tank Capacity:
8.0 L (2.1 US gal)
Crash Safety:
N/A (Motocross bikes are not subject to automotive safety ratings like NHTSA or Euro NCAP)
Braking System:
Hydraulic disc brakes front and rear
Suspension Features:
Adjustable front forks (compression, rebound, spring preload) and rear shock (rebound, compression, spring preload) for optimized handling and stability.
Frame Construction:
Aluminum alloy frame for light weight and rigidity
Oil Change:
Every 10-15 hours of riding or as per manual recommendation (engine oil and transmission oil often shared or separate depending on design).
Air Filter:
Clean/replace after every few rides or if heavily soiled
Spark Plug:
Inspect and clean/gap every 20-30 hours, replace as needed.
Valve Clearance:
Inspect every 30-50 hours (critical for four-stroke performance and longevity)
Engine Oil:
Yamaha recommends specific grades like Yamalube 4 (10W-40 or 20W-50 depending on climate). Manual will specify exact viscosity and API rating.
Coolant:
Permanent type ethylene glycol-based coolant, 50/50 mix with distilled water. Manual will specify type and capacity.
Brake Fluid:
DOT 4 hydraulic brake fluid
Common Problems:
For this era, potential issues include valve seat wear, carburetor jetting sensitivity, clutch wear, and occasional water pump seal leaks. The manual will provide detailed diagnosis and repair for these.
Rebuild Considerations:
Top-end rebuilds (piston, rings, valves) are common maintenance items for high-performance motocross bikes.
Yamaha Legacy:
Yamaha has a long and storied history in motorcycle racing, particularly in motocross, known for performance and innovation.
Yzf Lineage:
The YZ250F was a groundbreaking model for Yamaha, marking a significant shift to four-stroke technology in the highly competitive 250cc class. It replaced the highly successful YZ250 two-stroke.
Manufacturing Location:
Primarily Japan
Production Years:
First introduced in 2001, the 2003 model year saw continued refinement.
