The Yamaha XS400, produced from 1977 through 1982, represents a significant offering in the mid-weight parallel-twin motorcycle segment. Known for its balanced performance and everyday usability, the XS400 series, encompassing models like the XS400G, H, J, K, SH, SJ, and SK, was engineered to provide a reliable and enjoyable riding experience. Its air-cooled, 4-stroke, DOHC parallel-twin engine, typically displacing around 392 cc, delivered approximately 35-45 horsepower, making it a capable machine for both commuting and spirited riding. The model was recognized for its general reliability and smooth engine operation, positioning it as a strong competitor against other offerings from Honda, Kawasaki, and Suzuki during its era. This comprehensive service repair manual is designed to assist professional technicians and experienced DIY mechanics in maintaining and repairing the Yamaha XS400. It covers a wide array of systems, including detailed procedures for engine disassembly, assembly, tuning, lubrication, cooling, ignition, and fuel systems, as well as drivetrain components like the clutch and transmission. Furthermore, the manual provides in-depth guidance on chassis elements such as suspension and brakes, electrical systems, and bodywork. With clear, step-by-step instructions, diagnostic procedures, and extensive technical specifications, this manual serves as an indispensable resource for all repair, maintenance, rebuild, and restoration needs for your XS400. 🏷️ Basic Information Identification Make: Yamaha Model: XS400 Production Years Covered: 1977, 1978, 1979, 1980, 1981, 1982 Codes Model Code Range: XS400G, XS400H, XS400J, XS400K, XS400SH, XS400SJ, XS400SK (Specific codes may vary by market and sub-model) 👋 Introduction Market Position Market Niche: Sportbike/Standard Motorcycle for its era, popular for its balance of performance and everyday usability. Competitive Analysis Key Competitors: Honda CB550/CB650, Kawasaki KZ550/KZ650, Suzuki GS550/GS650. Key Features Manual Benefits: Empowers owners and technicians with comprehensive, detailed information for all repair and maintenance needs, mirroring professional technician resources. Manual Presentation: Structured with numbered steps, notes, cautions, warnings, and clear figure references for ease of use. 📋 Manual Details Coverage Areas Manual Type: Full Service Repair Manual Primary Coverage: Repair, Maintenance, Rebuild, Refurbish, Restoration Page Count Estimated Page Count: Refer to individual manual; typically 200-500+ pages for comprehensive coverage. Manual Type Intended Audience: Professional Technicians and Experienced DIY Mechanics Language Language: English Format File Format: PDF (Portable Document Format) 📖 Manual Coverage Systems Covered Engine Systems: Engine disassembly, assembly, tuning, lubrication, cooling system, ignition system, fuel system (carburetors), exhaust system. Drivetrain Systems: Clutch, transmission, final drive (chain and sprocket), gearbox overhaul. Chassis Systems: Frame, front suspension (forks), rear suspension (shocks/swingarm), steering system, wheels, brakes (front and rear). Electrical Systems: Wiring diagrams, lighting system, starting system, charging system, battery, ignition coil, starter motor, switches. Bodywork And Trim: Body panels, fuel tank, seat, fenders, handlebars, controls, instruments, trim components. Procedures Included Maintenance Procedures: Oil changes, filter replacements, spark plug inspection/replacement, chain adjustment, brake fluid changes, carburetor synchronization. Diagnostic Procedures: Troubleshooting common problems, electrical fault finding, carburetor performance diagnosis. Repair Procedures: Detailed step-by-step instructions for component removal, installation, and repair. Rebuild Procedures: Comprehensive instructions for engine and transmission overhauls. Technical Depth Depth Of Coverage: Detailed, encompassing everything from routine maintenance to complete engine and transmission rebuilds. 📊 Manual Specifications File Format Print Quality: Full Printable (High Resolution for clear printing) Binding Type Binding Type: Digital (PDF - Printable) Paper Type Paper Type Equivalent: N/A (Digital format) Delivery Delivery Method: Instant Download Requirements Required Software: Adobe PDF Reader, WinRAR (for potential archive extraction) Compatibility Operating Systems: All Versions of Windows & Mac ⚙️ Engine Specifications Primary Engine Engine Type: Air-cooled, 4-stroke, DOHC, Parallel-Twin Displacement: 392 cc (approx.) Bore X Stroke: 69.0 mm x 51.4 mm (typical for early models) Compression Ratio: 9.2:1 (typical) Performance Horsepower: Approximately 35-45 HP @ 8000-9000 RPM (varies by year and specific model tune) Torque: Approximately 30-35 Nm @ 6000-7000 RPM (varies by year and specific model tune) Fuel System Carburetor Type: Dual Mikuni VM34 or similar constant velocity carburetors Fuel Capacity: Approximately 12-15 Liters (varies by model) Ignition System Ignition Type: Electronic Ignition (CDI) or TCI depending on the specific year 🔧 Transmission Standard Transmission Type: 6-speed, constant mesh Features Clutch Type: Wet, multi-plate Final Drive: Chain drive 📐 Dimensions Weights Dry Weight: Approximately 170-180 kg (varies by model) Overall Length: Approximately 2100-2200 mm (varies by model) Overall Width: Approximately 750-850 mm (varies by model) Wheelbase: Approximately 1400-1450 mm (varies by model) Seat Height: Approximately 780-800 mm (varies by model) 🛡️ Safety Features Active Features Braking System Front: Single Disc Brake (some later models may have dual discs) Braking System Rear: Drum Brake Passive Features Frame Type: Steel Double Cradle Frame Lighting: Halogen Headlight, LED/Incandescent Tail and Turn Signals 💡 Technology Features Infotainment Instrumentation: Analog speedometer, tachometer, odometer, trip meter, neutral indicator, oil pressure warning light, high beam indicator. Driver Assistance ABS: Not available. Connectivity Charging System: Alternator with external regulator (or internal on later models). 🔧 Maintenance Service Intervals Oil Change Interval: Typically every...