2004 Harley-Davidson FLSTFI Fat Boy Technical Analysis & Specification Breakdown
Built around Harley-Davidson's custom - cruiser motorcycle platform, the 2004 Harley-Davidson FLSTFI Fat Boy utilizes a 1449 cc (88.4 cu in) air-cooled v2, four-stroke layout. In factory specification, peak output is rated at 62.5 HP (45.6 kW) at 5,400 rpm while maximum torque reaches 102 Nm (75.2 lb-ft) at 3,500 rpm, transferring power to the rear wheel through a 5-speed gearbox and belt final drive. With a specific output of 43.1 HP per liter and a 1,900 rpm working window between peak torque (3,500 rpm) and peak power (5,400 rpm), the engine character is prioritizing low-RPM tractability, mechanical longevity and relaxed throttle response over peak redline numbers.
On the scales, the FLSTFI Fat Boy measures 324 kg (714 lbs) wet (curb), translating to a power-to-weight ratio of 0.19 HP/kg (5.18 kg per horsepower). Rider ergonomics and chassis geometry center around a 645 mm (25.4 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,630 mm (64.2 in) wheelbase engineered for planted straight-line stability. The 18.9-liter (5 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Harley-Davidson archive, this model family spans 4 indexed model years from 2002 to 2006, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
43.1 HP/L
Power-to-Weight
0.19 HP/kg (5.18 kg/HP)
Power Band Window
3,500–5,400 rpm
Standover Height
645 mm (25.4 in)
Engine
Displacement1449.0 ccm (88.42 cubic inches)
Engine TypeV2, four-stroke
Engine DetailsV2, four-stroke
Power62.5 HP (45.6 kW)) @ 5400 RPM
Torque102.0 Nm (10.4 kgf-m or 75.2 ft.lbs) @ 3500 RPM
Seat Height645 mm (25.4 inches) If adjustable, lowest setting.
Overall Length2396 mm (94.3 inches)
Fuel Capacity18.90 litres (4.99 US gallons)
Oil Capacity3.30 litres (3.49 US quarts)
Other
Color OptionsVivid black, brilliant silver, sierra red, smokey gold, luxury blue, glacier white pearl, lava red sunglo, two-tone impact blue and vivid black, two-tone luxury teal and brilliant silver, two-tone sierra red and brilliant silver, two-tone smokey gold and
Notes
Black powder-coated engine with chrome covers; fat front forks; solid disc front and rear wheels; large chrome headlight with fork nacelle
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.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
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.
