Segment:
Performance Motocross/Off-Road Motorcycle
Target Audience:
Motocross racers, off-road enthusiasts, and owners seeking in-depth maintenance and repair knowledge for their Yamaha YZ250.
Competitors:
KTM 250 EXC, Honda CR250R, Suzuki RM250, Kawasaki KX250.
Key Selling Points Model:
Renowned for its powerful 2-stroke engine, excellent handling, and robust construction. A dominant force in the open-class motocross category during its production run.
Manual Value Proposition:
Provides essential technical information to maintain peak performance, diagnose issues, and perform complex repairs, saving time and money on servicing.
Manual Utility:
Indispensable for owners who want to understand their machine intimately, perform their own maintenance, and maximize the lifespan and performance of their YZ250.
Engine Mechanical:
Detailed breakdown of the 2-stroke engine, including cylinder, piston, crankshaft, connecting rod, bearings, and seals. Covers assembly, disassembly, inspection, and replacement procedures.
Engine Tuning:
Information on carburetor adjustments, jetting, and ignition timing for optimal performance. Includes guidance on emissions control systems where applicable.
Transmission Drivetrain:
Complete coverage of the 5-speed gearbox, including gear selection, clutch operation, gear ratios, shifting mechanisms, and lubrication.
Suspension Front:
In-depth details on the Kayaba (KYB) SSS (Speed Sensitive System) front forks, including disassembly, assembly, oil levels, damping adjustments, and seal replacement.
Suspension Rear:
Comprehensive coverage of the KYB rear shock absorber, including linkage disassembly, shock absorber servicing, spring preload adjustment, and damping adjustments.
Braking System:
Detailed procedures for front and rear hydraulic disc brakes, including caliper overhaul, master cylinder servicing, fluid replacement, bleeding procedures, and pad/rotor replacement.
Fuel Delivery:
Information on the fuel tank, fuel lines, and the Mikuni VM38 carburetor, including cleaning, jetting, and float adjustment.
Cooling System:
Coverage of the liquid cooling system, including radiator, water pump, hoses, and coolant specifications.
Electrical Ignition:
Details on the ignition system, including CDI unit, spark plug, and related components. Includes basic troubleshooting for electrical issues.
Chassis Frame:
Information on the aluminum alloy frame, subframe, and footpegs. Includes inspection for damage and alignment.
Wheels Tires:
Specifications for wheel bearings, spokes, tires, and recommended tire pressures. Includes wheel removal and installation procedures.
Lubrication System:
Guidance on premix ratios for the 2-stroke engine and transmission oil specifications.
Routine Maintenance:
Step-by-step guides for tasks such as air filter cleaning, spark plug replacement, chain adjustment, and general inspection.
Engine Rebuild:
Comprehensive instructions for complete engine disassembly, component inspection, part replacement, and reassembly, including critical torque specifications.
Suspension Servicing:
Detailed procedures for servicing both front and rear suspension units, including oil changes, seal replacements, and internal component adjustments.
Brake System Overhaul:
Instructions for rebuilding brake calipers and master cylinders, replacing brake lines, and performing complete brake fluid flushes and bleeds.
Carburetor Adjustment Rebuild:
Detailed guidance on disassembling, cleaning, reassembling, and adjusting the Mikuni VM38 carburetor for optimal fuel delivery.
Electrical Diagnostics:
Basic troubleshooting steps for common electrical issues, including ignition system checks and lighting system troubleshooting.
Troubleshooting Guides:
Problem-solving sections addressing common symptoms and their potential causes and solutions.
Assembly Disassembly:
Clear, sequential instructions for removing and installing major components and sub-assemblies.
Depth Level:
Comprehensive Workshop Level
Detail Level:
Suitable for experienced DIY mechanics and professional technicians. Covers everything from basic maintenance to complete engine and suspension rebuilds.
Diagnostic Capabilities:
Includes detailed diagnostic procedures for identifying and resolving mechanical and electrical faults.
Length:
Approx. 82.7 inches (2100 mm)
Width:
Approx. 32.3 inches (820 mm)
Height:
Approx. 50.4 inches (1280 mm)
Dry Weight:
Approx. 217 lbs (98.5 kg)
Wet Weight:
Approx. 231 lbs (105 kg) (with all fluids)
Ground Clearance:
Approx. 14.0 inches (355 mm)
Wheelbase:
Approx. 57.7 inches (1465 mm)
Seat Height:
Approx. 38.6 inches (980 mm)
Fuel Capacity:
Approx. 2.4 gallons (9 liters)
Oil Change Transmission:
Every 10-15 hours of riding, or as specified in the manual for regular use. More frequent changes recommended for competitive use.
Air Filter Cleaning:
Clean after every few rides, or more frequently in dusty conditions. Refer to manual for specific procedure.
Spark Plug Check:
Inspect every 10-20 hours, replace as needed. Manual provides recommended spark plug type and gap.
Piston Ring Replacement:
Typically recommended every 40-60 hours of riding, or based on compression testing. Manual details wear limits and inspection criteria.
Top End Rebuild:
Recommended every 80-120 hours of riding, involving piston, rings, and potentially the cylinder bore. Manual provides detailed procedures and specifications.
Transmission Oil:
Yamaha specifically recommends Yamalube Gear Oil 10W-40, or equivalent API GL-4 SAE 80W hypoid gear oil. Capacity typically 0.65 liters.
Coolant:
Mixture of 50% high-quality ethylene glycol-based antifreeze and 50% distilled water. Capacity typically 1.03 liters.
Brake Fluid:
DOT 4 hydraulic brake fluid is recommended. Manual specifies exact type and bleeding procedures.
Common Wear Items:
Clutch plates, brake pads, wheel bearings, steering head bearings, swingarm bearings, and fork seals are common wear items subject to regular inspection and replacement.
Engine Performance Degradation:
Loss of compression, poor idling, and reduced power can indicate worn piston rings, cylinder bore, or reed valve issues, all covered in the manual.
Suspension Leaks:
Fork seal leaks and rear shock seal leaks are common due to the demanding nature of off-road riding. Manual provides detailed seal replacement procedures.
