Basic Information Identification Make: Yamaha Model: XS400 Model Variant: Standard (all styles covered) Codes Engine Codes: Not specified, but typically includes variations like 2N4, 4G5, 4R4 for this generation. Introduction Market Position Target Audience: Owners of Yamaha XS400 motorcycles from 1977-1982, ranging from amateur enthusiasts to professional mechanics seeking authentic factory repair information. Competitive Analysis Value Proposition: Provides complete, accurate, and detailed factory service information at a fraction of the cost of professional repair, enabling owners to maintain and repair their motorcycles effectively and affordably. Key Features Manual Features: Hundreds of pages, detailed substeps, notes/cautions/warnings, numbered instructions, bold figure numbers, detailed illustrations/drawings/photos, enlarged insets, numbered table of contents, comprehensive electrical troubleshooting and wiring diagrams. Manual Details Coverage Areas Years Covered: 1977, 1978, 1979, 1980, 1981, 1982 Page Count Estimated Page Count: Hundreds of pages (exact count not provided, but typical for factory service manuals of this era). Manual Type Type: Workshop Service Repair Manual Language Language: English Format Delivery Format: PDF Download Manual Coverage Systems Covered Major Systems: Engine, Chassis, Electrical System, Fuel System, Lubrication, Cooling, Drivetrain, Suspension, Brakes, Wheels and Tires, Bodywork, Troubleshooting. Procedures Included Repair Procedures: Complete disassembly and reassembly, engine tuning, carburetor adjustment, electrical system diagnostics and repair, brake system maintenance, suspension overhaul, routine maintenance, troubleshooting common problems. Technical Depth Depth: Comprehensive, covering both routine maintenance for the do-it-yourselfer and in-depth repair and diagnostic procedures for experienced mechanics. Includes step-by-step instructions with detailed illustrations. Manual Specifications File Format Format: PDF Print Quality Printability: Printable without restriction, allowing users to print entire manual or selected pages. Binding Type Binding Type: N/A (Digital Download) Paper Type Paper Type: N/A (Digital Download) Engine Specifications Primary Engine Engine Type: Air-cooled, 4-stroke, DOHC parallel-twin. Performance Bore X Stroke: Typically 69.0 mm x 62.0 mm (varies slightly by specific model within the generation). Displacement: 392 cc to 425 cc (depending on specific model variant within the years). Horsepower: Estimated 27-33 HP at 7,500-8,000 RPM (factory specifications vary). Torque: Estimated 23-26 lb-ft at 6,000-6,500 RPM (factory specifications vary). Fuel System Carburetion: Dual Mikuni VM series constant velocity carburetors (e.g., VM26SS or VM28SS). Fuel Type: Unleaded gasoline, 87 octane or higher recommended. Fuel Tank Capacity: Approximately 10-12 liters (varies by model variant). Transmission Standard Type: Constant mesh 5-speed sequential gearbox. Optional Optional Transmissions: Not applicable; all models in this generation featured a 5-speed manual transmission. Features Clutch Type: Wet multi-plate clutch. Final Drive: Chain drive. Dimensions Exterior Overall Length: Varies by model, typically around 2100-2200 mm. Overall Width: Varies by model, typically around 750-850 mm. Seat Height: Varies by model, typically around 780-820 mm. Weights Dry Weight: Approximately 170-185 kg (varies by model variant). Wet Weight: Approximately 185-200 kg (estimated, varies by fluid levels). Wheelbase: Approximately 1400-1450 mm. Safety Features Ratings Safety Ratings: N/A (Motorcycle safety standards and ratings were less standardized during this period compared to modern vehicles). Active Features Braking System: Front: Single disc brake with hydraulic caliper. Rear: Drum brake. Lighting: Halogen headlight, taillight, turn signals. Passive Features Frame Construction: Steel tube frame (e.g., double cradle). Technology Features Infotainment Infotainment System: N/A (Pre-dates modern infotainment systems; basic analog instrumentation). Driver Assistance Driver Assistance Features: N/A (No electronic driver assistance features common to modern vehicles). Connectivity Connectivity Features: N/A (No modern connectivity features). Maintenance Service Intervals Oil Change Interval: Recommended every 3,000-5,000 km or 6-12 months, whichever comes first. Specific interval detailed in manual. Valve Clearance Check: Recommended at 10,000-15,000 km or as per manual's detailed schedule. Fluid Specifications Engine Oil Type: Yamaha recommends SAE 10W-40 API SE or SF grade engine oil. Manual will specify exact viscosity and API rating. Engine Oil Capacity: Approximately 2.0-2.3 liters with filter change. Exact capacity detailed in manual. Brake Fluid Type: DOT 3 or DOT 4 hydraulic brake fluid for the front disc brake. Manual will specify exact type. Fork Oil Type: Yamaha No. 10 or equivalent 10W fork oil. Manual will specify exact viscosity and volume. Known Issues Common Problems: Carburetor synchronization and tuning, cam chain noise (tensioner issues), electrical connector corrosion, brake system maintenance (especially drum brake adjustment), valve seat wear over high mileage. Vehicle History Brand Heritage Yamaha Motorcycles: Yamaha Motor Company, established in 1955, has a rich history in motorcycle manufacturing, known for innovation, performance, and reliability across various disciplines. Model Evolution Xs400 Lineage: The XS400 was a key model in Yamaha's lineup during the late 1970s and early 1980s, representing a popular segment of mid-displacement parallel-twin motorcycles. It evolved through various iterations, including shaft drive (XS400SE) and specialized models, but this manual covers the core chain-drive variants. Production Manufacturing Era: The XS400 model line saw production from the late 1970s through the mid-1980s, with this specific manual focusing on the initial and highly influential generation. Awards & Recognition Recognitions Historical Acclaim: The XS400 series was generally well-regarded for its balance of...