Era Significance:
The Duo Glide 74 OHV was a flagship model for Harley-Davidson in the late 1950s, representing a blend of classic styling and V-twin power, catering to riders seeking performance and the iconic Harley-Davidson experience.
Key Competitors:
Competed primarily with other American V-twin motorcycles of the era, such as Indian (though Indian's production was waning), and other large-displacement cruisers. Its established brand loyalty and performance made it a dominant force.
Model Distinction:
The 'Duo Glide' name signified the introduction of hydraulic front and rear suspension, a significant comfort improvement over earlier 'Springer' forks. The 74 OHV engine was the powerhouse of the lineup.
Systems Covered:
Engine, Transmission, Chassis, Electrical, Fuel System, Brakes, Wheels, Handlebar, Forks, Seats, Gearcase, Crankcase, Clutch, Starter, Wiring, Spark Plugs, Horn, Battery, Instruments
Type:
Service Repair Manual
Engine Mechanical:
Detailed breakdown and assembly of the 74 OHV engine, including cylinder, cylinder head, crankcase, gearcase, and clutch.
Engine Performance:
Information on engine tuning, timing, and common performance adjustments for the 74 cubic inch OHV V-twin.
Transmission And Drivetrain:
Service procedures for the transmission, starter, and primary drive systems.
Chassis And Frame:
Detailed coverage of frame inspection, repair, and component mounting.
Suspension And Steering:
Service and adjustment procedures for the front forks and steering components.
Braking System:
Maintenance, inspection, and repair of the braking system (likely drum brakes for this era).
Wheels And Tires:
Information on wheel maintenance, spoke tension, and tire installation.
Fuel And Carburetion:
Service and adjustment for the fuel system, including carburetor maintenance.
Electrical System:
Comprehensive wiring diagrams, battery maintenance, horn operation, and instrument cluster troubleshooting.
Ignition System:
Details on spark plugs, ignition timing, and related components.
Maintenance:
Regular service tasks, lubrication, filter changes, and general upkeep.
Troubleshooting:
Diagnostic guides for identifying and resolving common mechanical and electrical issues.
Repair And Rebuild:
Step-by-step instructions for disassembling, repairing, and reassembling major vehicle components.
Component Adjustment:
Procedures for adjusting clutch, brakes, carburetor, and other critical systems.
Wiring Diagrams:
Detailed, comprehensive wiring schematics for troubleshooting and repair of the electrical system.
Torque Specifications:
Essential torque values for critical fasteners throughout the motorcycle, ensuring proper assembly and preventing component failure.
Special Tools:
Identification and usage of specialized tools required for specific repair or adjustment procedures.
Depth:
Comprehensive, suitable for both novice and experienced mechanics. Covers everything from basic maintenance to complete engine overhauls and electrical system diagnostics.
Engine Type:
Air-cooled, 45-degree V-twin, OHV (Overhead Valve)
Displacement:
74 cubic inches (approx. 1213 cc)
Bore X Stroke:
Typically around 3.4375 in. x 4.25 in. (specifics may vary, refer to manual for exact figures)
Compression Ratio:
Varied by model year and tune, typically in the range of 7.0:1 to 8.0:1
Horsepower Estimate:
Estimated 40-50 HP (exact figures not always officially published for this era, but indicative of strong torque)
Torque Estimate:
High torque output due to large displacement, ideal for cruising and pulling.
Carburetor Type:
Typically Linkert carburetors, with later models potentially transitioning. Manual will cover specific models.
Ignition Type:
Battery and Coil ignition, distributor (manual will specify)
Oil System:
Total Loss oil system (oil is consumed, not recirculated). Manual will detail oil type and change intervals.
Type:
4-speed constant mesh, foot shift, hand clutch (standard for this era).
Options:
N/A (4-speed was standard for this model)
Gear Selection:
Foot-operated gear selector, hand-operated clutch lever.
Transmission Oil:
Specific gear oil type and viscosity (refer to manual for exact HD-specified oil, likely a multi-viscosity gear oil).
Wheelbase:
Approx. 60-62 inches (specific to model variation)
Length:
Approx. 88-92 inches (specific to model variation)
Dry Weight:
Approx. 550-600 lbs (highly dependent on accessories and specific configuration)
Fuel Capacity:
Approx. 3.5-4.5 gallons (tank size varied slightly)
Features:
Minimal by modern standards. Primarily focused on essential instruments like speedometer, ammeter, and oil pressure indicator. Manual covers instrument functionality.
Features:
N/A. This era of motorcycle did not feature electronic rider aids.
Features:
N/A. Connectivity was limited to the mechanical and electrical systems of the motorcycle itself.
Oil Change:
Frequent oil changes recommended due to the total loss system. Typically every 1,000-1,500 miles, or as specified in the manual. Manual will detail oil type and quantity.
Major Service:
Scheduled for valve adjustments, ignition timing checks, and comprehensive system inspections at intervals specified in the manual (e.g., every 5,000-10,000 miles).
Engine Oil Type:
Specific Harley-Davidson approved oil for the period, often a multi-viscosity oil like SAE 50 or 20W-50. Manual is critical for exact specification.
Fork Oil:
Specific fork oil viscosity (e.g., SAE 10W or similar). Manual will confirm exact type and capacity for front forks.
Transmission Oil:
Dedicated gear oil for the transmission. Manual specifies type and capacity.
Common Wear Items:
Wear on clutch plates, valve guides, and potential leaks from gaskets and seals are common. Ignition points and condensers require regular attention. Manual provides troubleshooting for these.
Electrical Components:
Wiring integrity and the reliability of older electrical components (generators, voltage regulators) can be a concern. Manual's wiring diagrams are invaluable.
Legacy:
Harley-Davidson boasts a long and storied history, synonymous with American motorcycle culture, performance, and individuality.
Duo Glide Development:
The Duo Glide series built upon the successful Panhead engine platform, introducing significant chassis improvements like hydraulic suspension, making it a more comfortable and capable touring machine than its predecessors.
Manufacturing Origin:
United States
