1958 Harley-Davidson FL Duo Glide Technical Analysis & Specification Breakdown
Built around Harley-Davidson's touring motorcycle platform, the 1958 Harley-Davidson FL Duo Glide utilizes a 1212.7 cc (74 cu in) air-cooled v2, four-stroke layout. In factory specification, peak output is rated at 55 HP (40.1 kW) at 4,800 rpm while maximum torque reaches 85.4 Nm (63 lb-ft) at 3,200 rpm, transferring power to the rear wheel through a 4-speed gearbox and chain final drive. With a specific output of 45.4 HP per liter and a 1,600 rpm working window between peak torque (3,200 rpm) and peak power (4,800 rpm), the engine character is prioritizing low-RPM tractability, mechanical longevity and relaxed throttle response over peak redline numbers.
On the scales, the FL Duo Glide measures 267 kg (589 lbs) dry, translating to a power-to-weight ratio of 0.21 HP/kg (4.85 kg per horsepower). Rider ergonomics and chassis geometry center around a 1,500 mm (59.1 in) wheelbase engineered for balanced agility and highway composure. The 14.19-liter (3.7 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Harley-Davidson archive, this model family spans 6 indexed model years from 1958 to 1964, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
45.4 HP/L
Power-to-Weight
0.21 HP/kg (4.85 kg/HP)
Power Band Window
3,200–4,800 rpm
Engine
Displacement1212.7 ccm (74.00 cubic inches)
Engine TypeV2, four-stroke
Engine DetailsPanhead V-twin engine
Power55.0 HP (40.1 kW)) @ 4800 RPM
Torque85.4 Nm (8.7 kgf-m or 63.0 ft.lbs) @ 3200 RPM
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Torque
Torque is useful for judging real-world pull, especially for touring, commuting and loaded riding.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
