🏷️ Basic Information Identification Make: Harley-Davidson Model: Knucklehead & Flathead Product Type: Workshop Service Repair Manual Applicable Years: 1940, 1941, 1942, 1943, 1944, 1945, 1946, 1947 👋 Introduction Market Position Market Position: Essential resource for owners and mechanics of vintage Harley-Davidson motorcycles from a pivotal era. Competitive Analysis Competitive Analysis: This manual is a definitive guide, providing the detailed, factory-level information necessary to maintain and repair these iconic machines, often surpassing the scope of generalized workshop manuals. Key Features Key Features: All-inclusive coverage of OHV Knucklehead and Side Valve Flathead models, step-by-step instructions with illustrations, troubleshooting guides, and essential technical data, enabling DIY repairs and significant cost savings. 📋 Manual Details Coverage Areas Systems Covered: Engine (OHV Knucklehead & Side Valve Flathead variants), Transmission, Chassis, Electrical System, Fuel System, Ignition System, Lubrication System, Brakes, Suspension, Frame, Bodywork, Tools, Specifications, Troubleshooting Page Count Page Count: Comprehensive (Exact page count not specified, but described as 'Complete' and 'A-Z') Manual Type Manual Type: Workshop Service Repair Manual Language Language: English Format Format: Downloadable Digital File (PDF compatible) 📖 Manual Coverage Systems Covered Engine Mechanical: Detailed disassembly, inspection, repair, and assembly of OHV Knucklehead and Side Valve Flathead engines, including cylinder head, cylinders, pistons, connecting rods, crankshaft, camshaft, timing gears, valves, valve guides, valve seats, oil pump, and lubrication system. Transmission Drivetrain: Service and repair procedures for the gearbox, clutch, drive chain, and related components. Electrical System: Wiring diagrams, troubleshooting for ignition system (generator, coil, distributor/points), lighting, horn, and battery charging system. Fuel System: Carburetor service and adjustment, fuel lines, fuel tank, and fuel pump (if applicable). Brakes: Maintenance and repair of drum brake systems. Suspension Steering: Fork service, shock absorber maintenance, and steering head bearing adjustments. Procedures Included Routine Maintenance: Oil changes, filter replacement, spark plug service, lubrication points, chain adjustment, brake adjustments, tire pressure checks. Diagnostic Troubleshooting: Step-by-step guides for identifying and resolving common mechanical and electrical issues. Component Rebuild: Detailed instructions for complete disassembly, cleaning, inspection, measurement, and reassembly of all major components. Special Tools Procedures: Information on specialized tools required for certain repairs and specific procedural techniques. Engine Timing: Setting ignition timing using points, condenser, and ignition coil; valve timing procedures. Cylinder Head Service: Removal, inspection, valve lapping, seal replacement, and reinstallation. Carburetor Rebuild: Complete disassembly, cleaning, and reassembly of Linkert carburetors with parts replacement guidance. Electrical Troubleshooting: Diagnosis of charging system failures, ignition problems, and lighting circuits using wiring diagrams. Wheel And Tire Service: Spoke wheel maintenance, bearing service, tire mounting, and balancing. Technical Depth Technical Depth: Comprehensive; covers everything from basic owner maintenance to full engine and transmission rebuilds, suitable for both amateur and professional mechanics. Diagnostic Charts: Inclusion of diagnostic flowcharts and symptom-based troubleshooting tables. Specification Tables: Extensive tables for clearances, torque values, tolerances, and measurements critical for proper assembly and performance. 📊 Manual Specifications File Format File Format: PDF (Portable Document Format) Print Quality Print Quality: High quality, clear text and images suitable for printing. Binding Type Binding Type: Digital (N/A for printed version, but implies printable pages) Paper Type Paper Type: Digital (N/A for printed version, but implies suitable for standard printing) ⚙️ Engine Specifications Primary Engine Engine Types: Overhead Valve (OHV) Knucklehead and Side Valve Flathead Engine Configuration: V-Twin Displacement Knucklehead: Typically 61 cubic inches (E-Series) and 74 cubic inches (F-Series), with variations. Displacement Flathead: Typically 74 cubic inches (U/UL series), with variations. Performance Horsepower Approx Knucklehead: Varies by specific model and tuning, but generally in the range of 30-40 HP. Torque Approx Knucklehead: Varies by specific model and tuning, but significant low-end torque characteristic of Harley-Davidsons. Fuel System Carburetor Types: Commonly equipped with Linkert carburetors (e.g., M-series, M-35, M-51). Fuel Type: Gasoline (lead content considerations for modern fuels if not rebuilt with appropriate materials). 🔧 Transmission Standard Transmission Type: 4-speed manual constant mesh, foot-shifted. Optional Optional Transmissions: N/A for this era, 4-speed was standard for these models. Features Clutch Type: Dry, multiple-disc. Gear Ratios: Specific gear ratios detailed within the manual for each model variant. 📐 Dimensions Exterior Wheelbase Typical: Varies by model, approximately 56-58 inches. Weights Dry Weight Typical: Varies by model, approximately 500-600 lbs. 🛡️ Safety Features Ratings Safety Ratings: N/A (No formal crash test ratings for motorcycles of this era) Active Features Active Safety Features: Drum brakes front and rear, mechanical operation. Passive Features Passive Safety Features: Sturdy steel frame, rider positioning. 💡 Technology Features Infotainment Infotainment Systems: N/A. Focus is on mechanical and electrical functionality, not modern infotainment. Driver Assistance Driver Assistance Features: N/A. These motorcycles are purely mechanical and analog. Connectivity Connectivity Features: N/A. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 1000-2000 miles, or annually, depending on usage. Specific intervals provided in manual. Engine Top End Overhaul: Varies greatly with usage and condition; manual provides guidance on inspection points. Fluid Specifications Engine Oil Type: Mineral-based motorcycle...