Segment:
High-performance sport ATV, positioned for aggressive trail riding and recreational use.
Competitors:
Competed against models like Honda TRX450R, Suzuki LT-R450, Polaris Predator 500, and Kawasaki KFX400/700.
Engine Power:
Renowned for its powerful 660cc engine, offering strong torque and acceleration.
Handling:
Agile handling and capable suspension system designed for off-road performance.
Durability:
Yamaha's reputation for building robust and reliable engines and chassis.
Engine Mechanical:
Detailed coverage of the 660cc liquid-cooled, SOHC, 4-valve, 5-valve engine.
Cooling System:
Radiator, fan, coolant circuits, thermostat operation and service.
Fuel System:
Carburetor (Mikuni BSR38) specifications, adjustments, cleaning, and overhaul.
Ignition System:
CDI unit, ignition timing, spark plug specifications, and troubleshooting.
Electrical System:
Wiring diagrams, lighting, battery, charging system (stator, regulator/rectifier), starter motor.
Transmission:
5-speed manual transmission with reverse, clutch operation, and internal component service.
Drivetrain:
Shaft drive, bevel gear case, front/rear driveshaft, differential (if applicable).
Suspension:
Front independent suspension (A-arms, shocks), rear swingarm, shock absorber adjustments and service.
Brakes:
Hydraulic disc brakes (front and rear), caliper service, pad replacement, brake fluid specifications.
Steering:
Handlebar assembly, steering shaft, tie rods, and steering bearing service.
Frame And Bodywork:
Frame inspection, body panel removal/installation, seat, fenders, and rack components.
Routine Maintenance:
Oil changes, filter replacements, chain adjustment, air filter cleaning, spark plug checks.
Troubleshooting Diagnostics:
Systematic diagnostic procedures for common performance issues, electrical faults, and mechanical problems.
Engine Overhaul:
Top-end rebuild (cylinder head, piston, rings), bottom-end service (crankshaft, bearings, seals).
Transmission Rebuild:
Disassembly, inspection, and reassembly of the gearbox and clutch components.
Carburetor Tuning:
Jetting, float level adjustment, idle speed, and mixture screw settings.
Electrical Component Testing:
Testing of stator output, regulator/rectifier function, battery condition, and starter solenoid.
Suspension Adjustments:
Preload, compression, and rebound damping adjustments for optimal ride handling.
Brake System Service:
Bleeding, caliper overhaul, pad and rotor replacement.
Wheel Bearing Service:
Replacement of front and rear wheel bearings.
Lubrication Points:
Identification and recommended lubrication for all critical points.
Depth:
Comprehensive. Covers routine maintenance to full engine and transmission rebuilds, including detailed troubleshooting and electrical diagnostics.
Engine Type:
4-stroke, liquid-cooled, SOHC, 5-valve
Bore X Stroke:
95.0 mm x 92.7 mm
Horsepower:
Approx. 45-50 hp (manufacturer figures often not explicitly stated, performance tune dependent)
Torque:
Strong mid-range torque delivery
Carburetor:
Mikuni BSR38 with throttle position sensor (TPS)
Oil Type:
Yamalube 4 (or equivalent) SAE 10W-40, API SG, JASO MA
Oil Capacity:
Approx. 2.2 L (with filter change)
Ignition System:
TCI (Transistor Controlled Ignition)
Engine Oil:
Every 1,000 km (620 miles) or 3 months, whichever comes first. Inspect more frequently for aggressive riding.
Air Filter:
Clean every 1,000 km (620 miles) or 3 months. Replace as needed.
Spark Plug:
Inspect every 1,000 km (620 miles). Replace as needed. Recommended plug: NGK CR7E
Valve Clearance:
Check every 3,000 km (1,860 miles) or 1 year. Intake: 0.09-0.13 mm; Exhaust: 0.13-0.17 mm.
Brake Fluid:
Replace every 2 years. Recommended fluid: DOT 4.
Engine Oil Spec:
Yamalube 4 (or equivalent) SAE 10W-40, API SG, JASO MA
Coolant Spec:
Permanent type antifreeze coolant mixed with distilled water at a 1:1 ratio. (e.g., Yamaha Yamalube Coolant)
Common Problems:
Early models may experience occasional issues with the starter clutch, cam chain tensioner, and carburetor jetting sensitivity to altitude/temperature changes. Overheating can occur under extreme conditions without proper airflow or if cooling system maintenance is neglected.