This workshop repair service manual provides comprehensive guidance for the Yamaha XS400 motorcycle, covering models produced between 1977 and 1982. The XS400 series, a significant entry in Yamaha's mid-weight motorcycle lineup, featured an air-cooled, four-stroke, parallel-twin engine with displacements ranging from approximately 392cc to 425cc. Known for its blend of performance, reliability, and distinctive styling, the XS400 series competed effectively in its market segment, offering a balanced riding experience that appealed to a wide audience. This manual addresses various sub-models, potentially including standard, Special, and Custom variants, ensuring broad applicability for owners and technicians. The purpose of this 317-page English-language manual is to serve as an authoritative resource for the maintenance, repair, and troubleshooting of the Yamaha XS400. It details a wide array of systems, including engine overhaul, fuel and ignition systems, transmission and drivetrain, electrical components, chassis and suspension, brakes, and bodywork. The manual offers step-by-step instructions for routine maintenance, complex repairs, and tune-up procedures, supported by essential technical specifications, torque values, and wiring diagrams. By providing in-depth information and diagnostic guidance, this manual empowers both experienced technicians and skilled enthusiasts to maintain the XS400 effectively, ensuring its optimal performance and longevity. 🏷️ Basic Information Identification Make: Yamaha Model: XS400 Model Generation: First Generation Codes Chassis Codes: 4G5, 12H, 2A6 (specific to sub-models/years within the range) Engine Codes: 4G5, 12H, 2A6 (specific to sub-models/years within the range) 👋 Introduction Market Position Historical Context: The Yamaha XS400 series represented Yamaha's entry into the mid-weight segment of the motorcycle market, offering a blend of performance, reliability, and style that appealed to a broad range of riders. Competitive Analysis Key Competitors: Competed against models like the Kawasaki KZ400, Honda CB400 series, and Suzuki GS400 during its production run. Key Features Model Variants: This manual likely covers various sub-models within the XS400 line, potentially including standard, Special, and Custom variants, which may have minor differences in styling and some components. Manual Value Proposition: Empowers owners and technicians with dealership-level repair and maintenance knowledge, enabling cost savings and ensuring proper upkeep. 📋 Manual Details Coverage Areas Model Years Covered: 1977, 1978, 1979, 1980, 1981, 1982 Page Count Page Count: 317 Manual Type Manual Type: Workshop Repair Service Manual Language Language: English Format Format: PDF 📖 Manual Coverage Systems Covered Engine Systems: Engine overhaul, disassembly and assembly, tuning, lubrication system, cooling system (if applicable), engine internals (pistons, rings, crankshaft, camshafts), valve train. Fuel System: Carburetor(s) disassembly, cleaning, adjustment, and synchronization; fuel lines, fuel tank, fuel pump (if applicable). Ignition System: Ignition timing, spark plugs, ignition coils, CDI unit, wiring, charging system (stator, rectifier/regulator). Transmission And Drivetrain: Gearbox disassembly and assembly, clutch operation and adjustment, drive chain maintenance and adjustment, internal transmission components. Electrical System: Wiring diagrams, lighting (headlight, taillight, indicators), starter system, battery, switches, fuses, instrumentation. Chassis And Suspension: Front fork disassembly, servicing, and adjustment; rear shock absorber servicing or replacement; swingarm maintenance; wheel bearing service; steering head bearing service. Brakes: Front and rear brake system servicing (disc or drum), brake caliper overhaul, brake pad replacement, brake fluid bleeding, brake cable adjustment. Bodywork And Trim: Body panel removal and installation, seat, fenders, fuel tank mounting, minor cosmetic repairs. Exhaust System: Exhaust pipe and muffler removal/installation, gasket replacement. Procedures Included Routine Maintenance: Oil changes, filter replacement, spark plug replacement, chain lubrication and adjustment, brake adjustments, tire pressure checks, general inspections. Troubleshooting: Diagnostic procedures for common and uncommon issues, symptom-based troubleshooting guides. Repair And Overhaul: Detailed step-by-step instructions for component disassembly, repair, reassembly, and adjustment. Tune Up Procedures: Carburetor synchronization, ignition timing adjustment, valve clearance checks and adjustments. Special Tool Identification: Identification and use of specialized tools required for specific tasks and adjustments. Technical Depth Depth Of Coverage: Comprehensive, covering routine maintenance through complete engine and transmission rebuilds. User Level Assumption: Primarily targeted at mechanical technicians familiar with motorcycle service procedures, but accessible to skilled DIY enthusiasts. 📊 Manual Specifications File Format File Format: PDF Print Quality Printability: Printable Binding Type Binding Type: N/A (Digital Download) Paper Type Paper Type: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Engine Type: Air-cooled, four-stroke, parallel-twin Displacement: Approximately 392cc to 425cc (depending on specific sub-model and bore/stroke configurations) Bore X Stroke: Varies by specific model, e.g., 63.0 mm x 64.0 mm for some models. Compression Ratio: Typically around 9.0:1 to 9.5:1 Performance Horsepower Output: Approx. 27-36 HP (at the crankshaft), depending on year and tuning Torque Output: Approx. 23-30 lb-ft (at the crankshaft), depending on year and tuning Fuel System Carburetion: Dual Mikuni VM or BS series carburetors (e.g., 34mm) Fuel Type: Unleaded gasoline (octane rating specified in manual) Ignition Ignition System Type: CDI (Capacitor Discharge Ignition) Lubrication Oil Type: Yamaha recommends specific motorcycle-grade 4-stroke engine oil (e.g., SAE 20W-40 or 10W-40, depending on climate). Oil Capacity: Approx. 2.0 - 2.5 liters (with filter change), specific value in manual. 🔧...