🏷️ Basic Information Identification Make: Harley-Davidson Model: Duo-Glide Model Codes: FL, FLH Years: 1958-1959 Engine Designation: 74 OHV 👋 Introduction Market Position Market Position: Essential resource for owners and enthusiasts of the iconic Harley-Davidson Duo-Glide models, enabling self-sufficiency in maintenance and repair. Competitive Analysis Competitive Analysis: Direct competitor to official Harley-Davidson service documentation, offering comparable detail and technical accuracy for DIY mechanics and restorers. Key Features Key Features: Detailed, illustrated, factory-level information for troubleshooting, repair, and maintenance, facilitating cost savings and preservation of vintage motorcycles. 📋 Manual Details Coverage Manual Type: Service Repair Workshop Manual Coverage Areas: Complete service, repair, restoration, maintenance, rebuilding, diagnosis Format File Format: PDF (Downloadable, may be zipped) Delivery Method: Instant Digital Download Language Language: English 📖 Manual Coverage Systems Systems Covered: Engine (OHV V-Twin), Transmission, Chassis, Electrical System, Fuel System, Ignition System, Brakes (Front & Rear Drum), Suspension (Front Fork, Rear Shocks), Wheels & Tires, Bodywork & Trim, Lubrication System, Cooling System (Air-Cooled), Exhaust System, Frame, Handlebars, Controls Procedures Procedures Included: Routine Maintenance, Troubleshooting, Component Removal & Installation, Reassembly, Adjustment Procedures, Electrical Schematics & Diagnostics, Engine Rebuilds, Transmission Overhauls, Brake System Service, Suspension Tuning, Carburetor Service, Ignition Timing, Wiring Diagrams, Lubrication Schedules Depth Technical Depth: Comprehensive diagnostic and repair procedures, suitable for professional technicians and DIY enthusiasts. Includes detailed step-by-step instructions and clear illustrations. 📊 Manual Specifications File Quality File Quality: High quality, printable, zoomable illustrations, searchable text (typical for factory manuals). Content Features Content Features: Step-by-step instructions, troubleshooting guides, exploded views, detailed component breakdowns, part number references (implied for factory manual). Printability Print Quality: Printable on any computer and printer. Binding Type Binding Type: Not Applicable (Digital Download) Paper Type Paper Type: Not Applicable (Digital Download) Accessibility Accessibility: Compatible with all operating systems (Windows, Linux, Mac) via PDF reader. Requires internet connection for download and potentially unzipping software (WinZip/WinRAR). ⚙️ Engine Specifications Primary Engine Engine Type: Overhead Valve (OHV) V-Twin Engine Displacement: 74 cubic inches (approximately 1213 cc) Performance Horsepower Approximate: Estimated 50-60 HP (Exact figures vary by specific tuning and year) Torque Approximate: Not specified in product info, but known for strong low-end torque. Fuel System Carburetor Type: Typically Linkert carburetor or early Keihin models Ignition System Ignition Type: Battery and Coil Ignition (Magneto ignition also present on some earlier models or variants) Lubrication Oil System: Dry Sump Lubrication System with oil tank separate from the crankcase. 🔧 Transmission Standard Transmission Type: 4-speed constant mesh manual transmission Features Clutch Type: Wet multi-plate clutch Fluid Specifications Transmission Oil Type: Refer to manual for specific Harley-Davidson or SAE 50 gear oil recommendations. Avoid modern multi-viscosity oils unless specifically approved. 📐 Dimensions Exterior Wheelbase Approximate: Approximately 60.5 inches (1537 mm) Weights Dry Weight Approximate: Approximately 570-600 lbs (259-272 kg) 💡 Technology Features Infotainment Infotainment Features: None (This era of motorcycle predates modern infotainment systems). Driver Assistance Driver Assistance Features: None (Basic instrumentation: speedometer, ammeter, oil pressure light). Electrical Electrical System: 6-volt electrical system, a significant feature of this era, requiring specific maintenance considerations. 🔧 Maintenance Service Intervals Oil Change Interval: Typically every 1000-2000 miles or annually, depending on usage. Refer to manual for precise intervals. Engine Tune Up: Regular checks of ignition timing, carburetor adjustment, and valve lash are crucial, with intervals often tied to mileage or annual service. Fluid Specifications Engine Oil Type: Harley-Davidson recommended straight-weight oils (e.g., SAE 30, 40, or 50) or specific motorcycle-specific oils meeting HD standards of the era. Refer to manual for exact viscosity and type. Brake Fluid Type: DOT 3 or DOT 4 brake fluid (if hydraulic brakes are equipped, though earlier models often used mineral oil in clutch systems). Known Issues Known Issues: Oil leaks (common with age), carburetor flooding/adjustment issues, electrical system reliability (points, condensers), wear on valve guides, transmission shifting precision. Parts Reference Parts Reference: Manual is expected to contain exploded views and potentially part numbers for critical components, aiding in sourcing correct replacements. 📚 Vehicle History Brand Heritage Brand Heritage: Harley-Davidson, founded in 1903, is an iconic American motorcycle manufacturer renowned for its powerful V-twin engines and classic styling. Model Evolution Model Evolution: The Duo-Glide (FL/FLH) replaced the Hydra-Glide and was the first Harley-Davidson to feature a swingarm rear suspension, significantly improving rider comfort and handling. It was succeeded by the Electra Glide. Production Production Period: 1958-1964 (Duo-Glide designation) Key Innovations: Introduction of hydraulic rear suspension (Duo-Glide name origin), improved frame rigidity. 🏆 Awards & Recognition Recognitions Recognitions: The Duo-Glide itself is a highly regarded classic motorcycle, celebrated for its design and pioneering suspension technology in its era. The manual provides the means to maintain this status.