2006 Harley-Davidson FLSTFI Fat Boy Technical Analysis & Specification Breakdown
Engineered by Harley-Davidson for the custom - cruiser motorcycle segment, the 2006 Harley-Davidson FLSTFI Fat Boy relies on a 1442.2 cc (88 cu in) air-cooled v2, four-stroke powerplant. In factory specification, peak output is rated at 67 HP (48.9 kW) at 5,250 rpm while maximum torque reaches 115.3 Nm (85 lb-ft) at 3,000 rpm, transferring power to the rear wheel through a 5-speed gearbox and belt final drive. With a specific output of 46.5 HP per liter and a 2,250 rpm working window between peak torque (3,000 rpm) and peak power (5,250 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 323.9 kg (714 lbs) wet (curb), translating to a power-to-weight ratio of 0.21 HP/kg (4.83 kg per horsepower). Rider ergonomics and chassis geometry center around a 627 mm (24.7 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,638 mm (64.5 in) wheelbase engineered for planted straight-line stability. The 18.92-liter (5 US gal) fuel tank paired with a rated consumption of 5.11 L/100 km provides an estimated theoretical range of roughly 370 km (230 miles) between fill-ups.
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
46.5 HP/L
Power-to-Weight
0.21 HP/kg (4.83 kg/HP)
Power Band Window
3,000–5,250 rpm
Theoretical Range
~370 km (230 mi)
Engine
Displacement1442.2 ccm (88.00 cubic inches)
Engine TypeV2, four-stroke
Engine DetailsV2, four-stroke
Power67.0 HP (48.9 kW)) @ 5250 RPM
Torque115.3 Nm (11.8 kgf-m or 85.0 ft.lbs) @ 3000 RPM
Compression8.9:1
Bore x Stroke95.3 x 101.6 mm (3.8 x 4.0 inches)
Valves/Cylinder2
Fuel SystemInjection. Electronic Sequential Port Fuel Injection (ESPFI )
Seat Height627 mm (24.7 inches) If adjustable, lowest setting.
Overall Length2395 mm (94.3 inches)
Fuel Capacity18.92 litres (5.00 US gallons)
Oil Capacity3.30 litres (3.49 US quarts)
Other
Color OptionsVivid black, brilliant silver, black pearl, deep cobalt, glacier white pearl, yellow pearl, brandy wine sunglo, two-tone chopper blue and brilliant silver, two-tone black cherry and black pearl, two-tone fire red pearl and vivid black, two-tone deep cobal
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.
