🏷️ Basic Information Identification Make: Yamaha Model: XS400 Year: 1981 Codes Model Code: Likely varies by market and specific variant (e.g., XS400-D, XS400-E) Engine Code: Likely 2G5 for the 1981 model year, specific variations may exist 👋 Introduction Market Position Target Audience: Professional technicians and serious DIY mechanics focused on the Yamaha XS400 1981 model. Competitive Analysis Value Proposition: Provides comprehensive, factory-level repair and maintenance information, eliminating the need for expensive physical manuals or dealership service. Key Features Instruction Style: Numbered instructions, bold figure numbers for illustration matching, detailed sub-steps, notes, cautions, and warnings. Visual Aids: Detailed illustrations, drawings, photos, and enlarged inset views for part identification. Organization: Numbered table of contents for quick information retrieval, combined troubleshooting and electrical procedures with wiring diagrams. 📋 Manual Details Coverage Areas Coverage: Comprehensive repair, maintenance, rebuilding, refurbishing, restoration, diagnostics, electrical service, troubleshooting, service schedules Page Count Page Count: Not specified in provided information, but described as 'very detailed' and covering 'everything you will ever need'. Manual Type Manual Type: Full Service Repair Manual Language Language: English Format Format: PDF 📖 Manual Coverage Systems Covered Engine Mechanics: Engine overhaul, cylinder head, cylinders, pistons, crankshaft, camshafts, valve train, lubrication system, cooling system (air-cooled), fuel system (carburetors), exhaust system. Fuel System: Carburetor adjustment, cleaning, rebuilding, synchronization, fuel lines, fuel tank, petcock. Ignition System: Ignition timing, coil testing, spark plug specifications, CDI unit diagnosis, wiring. Transmission Drivetrain: Gearbox inspection and repair, clutch operation and adjustment, final drive (chain and sprockets). Electrical System: Wiring diagrams, lighting system, charging system (alternator/stator, rectifier/regulator), starting system (starter motor, battery), instrumentation, electrical component testing and troubleshooting. Suspension Steering: Front fork overhaul, rear shock absorber service, steering head bearing adjustment and replacement. Brakes: Front and rear brake system (likely disc front, drum rear for this era/model), brake pad/shoe replacement, caliper/cylinder service, brake fluid replacement, bleeding procedures. Frame Bodywork: Frame inspection, seat, fenders, fuel tank mounting and removal, general disassembly/assembly. Procedures Included Maintenance: Regular service intervals, oil changes, filter replacement, chain adjustment, lubrication points, brake adjustments, spark plug replacement. Repair: Engine rebuild, transmission repair, carburetor overhauls, electrical component replacement, suspension servicing, brake system repair. Troubleshooting: Diagnostic procedures for common problems, fault finding for engine, electrical, and chassis systems. Diagnostics: Systematic troubleshooting guides, diagnostic flowcharts, specific electrical testing procedures. Technical Depth Depth: Professional technician level, suitable for comprehensive rebuilds and advanced diagnostics, with adequate data for DIY enthusiasts. 📊 Manual Specifications File Format File Format: PDF Print Quality Printability: Full Printable Binding Type Binding Type: Digital Download (not applicable for physical binding) Paper Type Paper Type: Digital Download (not applicable for physical paper type) Requirements Software Requirements: Adobe PDF Reader, WinRAR (for extraction if compressed) Compatibility Operating Systems: All Versions of Windows, Mac Delivery Method Delivery: Instant Download ⚙️ Engine Specifications Primary Engine Engine Type: Air-cooled, four-stroke, parallel-twin Displacement: 392 cc (23.9 cubic inches) Bore X Stroke: 63.0 mm x 64.0 mm (2.48 in x 2.52 in) Valve Actuation: DOHC (Double Overhead Camshafts), 2 valves per cylinder Performance Horsepower: Approximately 33-36 HP (varies slightly by specific model variant and tuning) Torque: Approximately 23-25 lb-ft (varies by specific model variant) Fuel System Carburetor Type: Twin Mikuni VM series (e.g., VM26 or VM28) or constant velocity (CV) carbs Fuel Capacity: Typically around 14 liters (3.7 US gallons) Engine Oil Oil Type: API SE or SF classification, SAE 20W-40 or 10W-40 motorcycle-specific oil Oil Capacity: Approximately 2.2 - 2.4 liters (with filter change) Spark Plugs Spark Plug Type: NGK B8ES or equivalent Spark Plug Gap: 0.7 - 0.8 mm (0.028 - 0.031 in) 🔧 Transmission Standard Transmission Type: Constant mesh, 5-speed sequential manual Features Clutch Type: Wet, multi-plate, diaphragm spring Final Drive: Chain drive Fluid Transmission Oil Type: Yamalube Gear Oil, or equivalent SAE 80 API GL-4 Transmission Oil Capacity: Approximately 1.1 liters 📐 Dimensions Exterior Length: Approximately 2175 mm (85.6 in) (typical for XS400 models) Width: Approximately 770 mm (30.3 in) (typical for XS400 models) Height: Approximately 1170 mm (46.1 in) (typical for XS400 models) Weights Dry Weight: Approximately 175 kg (386 lbs) Wet Weight: Approximately 188 kg (414 lbs) (with fluids) Weight Distribution: Generally balanced for motorcycle handling 🛡️ Safety Features Ratings Safety Standards: Designed to meet Japanese safety standards of the era; specific crash ratings not applicable to motorcycles. Active Features Braking System: Front: Disc brake; Rear: Drum brake (common configuration for this model) Lighting: Headlight, taillight, brake light, turn signals, license plate light. Passive Features Chassis Design: Steel frame for rigidity and rider support. Instrumentation: Speedometer, tachometer, warning lights (neutral, oil pressure, turn signals, high beam). 💡 Technology Features Infotainment Infotainment System: Not applicable; this is a 1981 motorcycle with basic instrumentation. Driver Assistance Rider Assistance: None; standard motorcycle controls. Connectivity Connectivity Features: Not applicable. 🔧 Maintenance Service Intervals Oil Change Interval: Every 3,000 km (1,860 miles) or 6 months, whichever comes first....