Market Segment:
High-performance motocross motorcycle, known for its powerful two-stroke engine and agile handling.
Key Competitors:
KTM 250 SX, Honda CR250R (previous years), Kawasaki KX250 (previous years), Suzuki RM250 (previous years).
Engine Character:
Renowned for its explosive power delivery and aggressive top-end, characteristic of potent two-stroke motocross engines.
Handling:
Lightweight and nimble chassis designed for aggressive cornering and precise control on track.
Manual Value:
Essential for owners to perform maintenance, repairs, and diagnostics, ensuring optimal performance and longevity of the highly tuned machine.
Engine:
Top-end (cylinder, piston, rings), bottom-end (crankshaft, connecting rod, bearings), lubrication, cooling (if applicable to model year), intake, exhaust.
Fuel System:
Carburetor (cleaning, adjustment, jetting), fuel lines, fuel tank.
Transmission:
Clutch (operation, adjustment, replacement), gear shifting mechanism, gearbox internals, lubrication.
Chassis:
Frame, subframe, swingarm, linkage system, bearings.
Suspension:
Front forks (disassembly, inspection, fluid replacement, seal replacement, adjustments), rear shock absorber (rebuild, fluid, nitrogen charge, adjustments).
Brakes:
Front and rear brake systems (hydraulic calipers, master cylinders, brake lines, brake pads, rotors), bleeding procedure.
Electrical System:
Ignition system (CDI, spark plug), lighting, wiring diagrams, battery, stator, rectifier/regulator (if applicable).
Wheels And Tires:
Hubs, spokes, rims, tire mounting and balancing, wheel bearings.
Controls:
Handlebars, levers, footpegs, throttle, clutch cable adjustments.
Bodywork:
Plastics, seat, fenders, graphics.
Maintenance:
Regular service checks, oil changes, filter cleaning/replacement, chain adjustment, spark plug replacement, air filter maintenance.
Troubleshooting:
Diagnostic flowcharts, common problems and solutions, symptom analysis.
Repair:
Step-by-step instructions for component disassembly, repair, and reassembly.
Rebuild:
Comprehensive guides for engine and suspension overhauls.
Specifications:
Detailed torque specifications, clearances, fluid levels, and settings.
Depth Level:
Comprehensive Factory Service Manual covering all aspects from basic maintenance to complete engine and suspension rebuilding.
Engine Configuration:
Single-cylinder, liquid-cooled, reed valve inducted, two-stroke.
Bore X Stroke:
66.4 mm x 72.0 mm
Compression Ratio:
8.6:1 (typical for this era YZ250)
Carburetor:
Keihin PWK38S (or similar 38mm flat slide carburetor)
Ignition:
Digital CDI (Capacitor Discharge Ignition)
Horsepower:
Approx. 45-47 HP (estimated at crankshaft, varies with tuning)
Torque:
Approx. 30-32 lb-ft (estimated at crankshaft, varies with tuning)
Fuel Type:
Unleaded gasoline, minimum 91 octane (octane requirement may vary based on tuning)
Fuel Mix Ratio:
50:1 (pre-mix, gasoline to 2-stroke oil) – precise ratio to be confirmed in manual.
Recommended Oil:
High-quality 2-stroke motorcycle oil meeting JASO FD or ISO-L-EGD standards.
Oil Change Interval:
Transmission oil: Every 15-20 hours of operation or annually. Engine oil (2-stroke pre-mix): Continuous.
Air Filter Cleaning:
After every few rides, or more frequently in dusty conditions. Detailed cleaning and oiling procedure in manual.
Spark Plug Inspection:
Every 10-15 hours of operation. Replacement as needed based on condition.
Chain Maintenance:
Lubricate and adjust chain tension every 5-10 hours of operation.
Engine Oil:
Yamaha 2-stroke premix oil or equivalent meeting specified standards.
Transmission Oil Type:
Yamaha Genuine Gear Oil 10W-40 or API GL-4 specification.
Coolant:
Permanent type antifreeze coolant (50% mixture with distilled water) for liquid-cooled models.
Clutch Wear:
Clutch plates can wear over time, especially with aggressive riding. Manual details inspection and replacement.
Carburetor Cleaning:
Regular cleaning and proper jetting are crucial for optimal performance of the two-stroke engine.
Suspension Seals:
Fork and shock seals can degrade over time, leading to leaks. Manual provides seal replacement procedures.
Yamaha Motorcycles:
Yamaha Motor Company is a Japanese manufacturer renowned for its long history of producing high-quality motorcycles, including a strong legacy in off-road racing.
Yz Series:
The YZ250 has been a dominant force in motocross for decades, consistently evolving with technological advancements in engine performance, suspension, and chassis design.
2008 Model Year:
The 2008 model year represents a refinement of the YZ250 platform, building upon previous generations with ongoing improvements in performance and handling characteristics.
Manufacturing Location:
Typically manufactured in Japan.
