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Introduction
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Market Position
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Segment:
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Entry-level to mid-range sport/standard motorcycle segment, often favored for its classic styling and manageable performance.
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Competitive Analysis
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Competitors:
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Competed against models like Honda CB400 Four, Kawasaki Zephyr 400, Suzuki GS500, and other similarly positioned naked or semi-faired Japanese motorcycles of the era.
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Key Features
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Styling:
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Classic Japanese motorcycle styling, often with a single headlight, round gauges, and a relatively upright riding position.
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Target Audience:
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Beginner riders, commuters, those seeking a stylish and reliable motorcycle with manageable power, and enthusiasts appreciating retro aesthetics.
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Manual Coverage
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Systems Covered
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Engine Systems:
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Engine assembly, disassembly, tuning, troubleshooting, cooling system, lubrication system, fuel system (carburetion), ignition system, exhaust system
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Transmission Drivetrain:
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Clutch, gearbox (transmission), final drive (chain and sprockets), lubrication
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Chassis Suspension:
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Front fork, rear shock absorber, swingarm, frame inspection and repair, steering system
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Braking System:
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Front and rear brake systems (likely hydraulic disc front, drum or disc rear), master cylinders, calipers, brake lines, bleeding procedures
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Electrical System:
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Battery, charging system (stator, regulator/rectifier), ignition system, lighting, starting system, wiring diagrams, instrument cluster, sensors
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Body Frame:
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Fuel tank, seat, fenders, side covers, handlebars, footpegs, fairings/bodywork (if applicable), fasteners
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Procedures Included
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Maintenance Procedures:
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Scheduled maintenance, oil changes, filter replacements, spark plug replacement, chain adjustment, brake fluid replacement, coolant replacement (if liquid-cooled), valve clearance adjustment
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Repair Procedures:
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Engine rebuilds, carburetor overhaul, transmission gear replacement, suspension component repair, electrical component diagnosis and replacement, brake system overhaul
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Troubleshooting Guides:
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Diagnostic charts, common problem identification, symptom-based troubleshooting for engine, electrical, and mechanical issues
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Special Tools:
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Identification and usage of specialized tools required for specific repair or maintenance tasks
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Technical Depth
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Depth:
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Comprehensive factory-level detail, suitable for professional technicians and experienced DIY mechanics. Covers everything from routine maintenance to complete engine and component overhauls.
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Engine Specifications
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Primary Engine
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Engine Type:
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Air-cooled, 4-stroke, DOHC, V-twin
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Displacement:
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249cc (249 cm³)
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Bore X Stroke:
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52.0 mm x 57.9 mm (approximate, typical for this displacement V-twin)
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Compression Ratio:
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9.5:1 (typical for this era and engine type)
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Performance
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Horsepower:
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Approx. 30-34 HP @ 8500 RPM (estimated, actual figures may vary slightly by market and specific tuning)
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Torque:
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Approx. 2.6 kgf·m @ 7000 RPM (estimated, actual figures may vary slightly by market and specific tuning)
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Fuel System
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Carburetion:
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Dual Mikuni carburetors (e.g., VM26 or similar 26mm constant velocity type), often with vacuum operated petcock.
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Fuel Type:
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Unleaded gasoline, 90-96 octane rating (RON+MON)/2 recommended.
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Lubrication
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Oil Type:
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Yamalube 4 (or equivalent SAE 10W-40 API SF or SG classified motorcycle oil)
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Oil Capacity:
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Approx. 2.0 liters (with filter change)
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Transmission
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Standard
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Transmission Type:
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Constant mesh, 6-speed sequential
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Clutch Type:
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Wet, multi-plate, cable-actuated
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Final Drive:
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O-ring sealed chain drive
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Features
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Gear Ratios:
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Specific gear ratios would be detailed in the manual, crucial for performance tuning and troubleshooting.
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Transmission Oil Type:
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Yamaha Gear Oil Hypoid 80W-90 (or equivalent API GL-4)
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Transmission Oil Capacity:
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Approx. 0.8 liters (specific figure from manual)
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Safety Features
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Ratings
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Safety Standards:
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Compliant with relevant Japanese domestic market (JDM) and international safety regulations of the early to mid-1990s. Specific crash test ratings are not typically published for motorcycles in the same way as cars.
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Active Features
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Braking System Features:
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Hydraulic disc front brake for strong stopping power, rear brake typically drum or disc depending on exact model variant. Often featured braided steel lines for improved feel.
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Lighting:
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Halogen headlight, tail light, brake light, and turn signals for visibility.
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Passive Features
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Frame Construction:
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Steel frame (likely diamond or cradle type) designed for stability and rider feedback.
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Tires:
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Tubeless tires (front: 110/80-17, rear: 140/70-17, typical sizes but refer to manual for exact specifications).
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Suspension Tuning:
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Adjustable front fork preload (some models) and rear suspension damping can be fine-tuned for rider preference and load.
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Maintenance
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Service Intervals
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Oil Change Interval:
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Every 3,000 km or 6 months, whichever comes first. (Refer to manual for precise intervals.)
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Air Filter Cleaning:
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Every 6,000 km or annually. Replacement as needed.
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Spark Plug Replacement:
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Every 10,000 km or annually. Specific plug type required (e.g., NGK CR9E or equivalent).
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Valve Clearance Check:
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Every 12,000 km or every two years.
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Brake Fluid Replacement:
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Every 2 years or as needed due to moisture absorption. Use DOT 3 or DOT 4 fluid.
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Fluid Specifications
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Engine Oil Viscosity:
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SAE 10W-40
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Engine Oil Standard:
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API SF or SG classification
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Brake Fluid Type:
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DOT 3 or DOT 4
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Coolant Type:
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N/A (Air-cooled engine)
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Known Issues
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Carburetor Issues:
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Potential for gumming or clogging of carburetors if fuel sits for extended periods, especially with ethanol-blended fuels. Synchronization may be required over time.
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Charging System:
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Regulator/rectifier failure can occur on older units, leading to battery charging issues. Stator output can degrade.
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Valve Guides:
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Wear in valve guides could lead to oil consumption over high mileage. Regular valve clearance checks are crucial.
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Electrical Connections:
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Corrosion on electrical connectors, particularly in exposed areas, can lead to intermittent faults. Periodic inspection and cleaning recommended.
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