🏷️ Basic Information Identification Make: Harley-Davidson Model: EL/FL Knucklehead Common Name: Knucklehead Engine Type: V-Twin OHV Codes Production Codes: EL (74 cubic inch), FL (80 cubic inch) 👋 Introduction Market Position Target Audience: Professional technicians, experienced DIY mechanics, and owners performing maintenance and repairs on Harley-Davidson Knucklehead models. Key Features Manual Attributes: Step-by-step repair procedures, critical specifications, illustrations/pictures, maintenance, disassembly, assembly, cleaning, reinstallation, troubleshooting guidance. Value Proposition Benefit To User: Empowers owners to perform informed maintenance and repairs, understand their motorcycle better, and potentially save on professional service costs. 📋 Manual Details Coverage Areas Years Covered: 1940, 1941, 1942, 1943, 1944, 1945, 1946, 1947 Page Count Estimated Page Count: Estimated 300-500+ pages (typical for comprehensive service manuals of this era) Manual Type Manual Type: Repair Service Manual / Workshop Manual Language Language: English Format File Format: PDF 📖 Manual Coverage Systems Covered Engine Mechanical: Complete disassembly, inspection, repair, and reassembly of the V-Twin OHV engine, including cylinder heads, cylinders, pistons, connecting rods, crankshaft, camshafts, valvetrain, oil pump, and timing gears. Fuel System: Carburetor service (e.g., Linkert M-series), fuel lines, fuel tank, and fuel petcock. Ignition System: Magneto ignition, spark plugs, ignition timing, and related components. Transmission: 4-speed constant mesh manual transmission service, clutch operation and adjustment, gear shifting mechanisms. Drivetrain: Primary drive chain, clutch, final drive chain, and sprockets. Electrical System: Wiring diagrams, lighting system (headlight, taillight, indicators), horn, battery, charging system (if applicable for the later years in this range, though often generator-based for this era), and control switches. Braking System: Mechanical rear drum brake system service, brake pedal, brake rods, and adjustment. Suspension System: Front fork service (e.g., Springer fork), rear suspension (rigid frame with sprung seat), wheel bearings, and steering head bearings. Chassis And Frame: Frame inspection, alignment, and related components. Bodywork And Trim: Fenders, fuel tanks, oil tanks, seat mounting, and controls. Procedures Included Maintenance: Routine maintenance, lubrication points, fluid checks and changes, ignition timing adjustments, carburetor tuning. Disassembly And Assembly: Detailed step-by-step procedures for complete vehicle and component disassembly and reassembly. Troubleshooting: Diagnostic charts and guidance for identifying and resolving common mechanical and electrical problems. Repair Procedures: Specific instructions for repairing worn or damaged components. Cleaning And Inspection: Guidelines for cleaning parts during disassembly and inspecting for wear or damage. Technical Depth Depth Of Coverage: Comprehensive; covers full rebuilds and advanced diagnostics, suitable for professional technicians and experienced DIY mechanics. 📊 Manual Specifications File Format File Format: PDF Print Quality Print Quality: Full Printable Accessibility Zoom Functionality: YES Requirements Software Requirements: Adobe PDF Reader & WinZip (or equivalent decompression software) Compatibility Operating System Compatibility: All Versions of Windows & Mac Delivery Method Delivery Method: Instant Download ⚙️ Engine Specifications Primary Engine Engine Displacement: 74 cu in (1208 cc) for EL, 80 cu in (1310 cc) for FL Engine Design Engine Configuration: 45-degree V-twin, OHV (Overhead Valve) Performance Horsepower Torque Range: While specific dyno figures are elusive for stock configurations from this era, the Knucklehead was known for its strong low-end torque and respectable horsepower for its time, generally in the range of 30-40 HP. Fuel System Carburetor Type: Typically Harley-Davidson Linkert M-series (e.g., M51, M74) or similar updraft carburetors. Lubrication System Oil System Type: Total loss oiling system (early models) or recirculating system with external oil tank and oil pump. 🔧 Transmission Standard Transmission Type: 4-speed, constant mesh manual transmission Features Clutch Type: Wet, multi-plate clutch Primary Drive: Chain drive within a separate primary case Final Drive: Roller chain drive to the rear wheel 📐 Dimensions Weights Dry Weight: Approximately 500-550 lbs (227-250 kg), depending on model variant and equipment. Wheelbase Wheelbase: Approximately 56-57 inches (1422-1448 mm) 🛡️ Safety Features Ratings Safety Standards: Vehicles from this era predate modern safety rating systems (e.g., NHTSA, Euro NCAP). Safety features are primarily mechanical. Active Features Braking System: Mechanical rear drum brake. Front brake typically a mechanical drum brake (depending on exact year/model variation, some early models might have had less effective braking). Passive Features Frame Construction: Robust steel frame, typically a rigid rear frame with sprung seat for rider comfort. 💡 Technology Features Infotainment Infotainment Systems: None. These motorcycles predate modern infotainment systems. Driver Assistance Assistance Features: None. Safety and operational features are purely mechanical. Connectivity Connectivity Options: None. 🔧 Maintenance Service Intervals Oil Change Interval: Frequent oil changes are critical for total loss systems or to maintain lubrication in recirculating systems. Typically every 1000-2000 miles, or as specified in the manual. Engine Tune Up: Regular checks of ignition timing, carburetor adjustment, and valve lash are recommended every few thousand miles. Fluid Specifications Engine Oil Type: High-quality motorcycle-specific engine oil, typically straight-weight mineral oil (e.g., SAE 50 or SAE 60, depending on ambient temperature and manual recommendation). Avoid modern multi-viscosity oils unless specifically indicated for vintage use. Transmission Oil Type: Gear oil suitable for manual transmissions, viscosity...