Harley-Davidson Fat Boy

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Harley-Davidson Fat Boy
ProductionSince 1990
  • Evolution (1990–1999)
    1,340 cc (82 cu in)
  • Twin Cam (2000–2017)[1]
    1,450 cc (88 cu in)
    1,584 cc (96.7 cu in)
  • Milwaukee-Eight (2018–present)
    1,746 cc (107 cu in)
    1,868 cc (114 cu in)
TransmissionChain (Primary) / Belt (final drive)
Wheelbase1,636 mm (64.4 in)

The Harley-Davidson Fat Boy, is a V-twin softail cruiser motorcycle with solid-cast disc wheels.[2]. Designed by Willie G. Davidson and Louie Netz, Harley-Davidson built a prototype Fat Boy in Milwaukee for the Daytona Bike Week rally at Daytona Beach in 1988 and 1989.[3][4] Fat Boys produced from 1990-2017 are coded FLSTF, and FLFB (& FLFBS) from 2018.

The name is said to come from the bike's "massive presence", and that the name gave a link to the earlier Harley-Davidson "Fat Bob" model.[5][dead link][6][unreliable source?][better source needed]

History and development[edit]

The Fat Boy's frame is derived from the 1984 "Softail" which appears to have a rigid hardtail chassis but which in fact has a swinging arm with concealed springs that was originally designed in a Missourian garage in the 1970's by "a mechanical engineer" named Bill Davis and later Patented in 1976.[7] Willie G the grandson of Harley-Davidson co-founder William A. Davidson originally turned down engineer Bill Davis' softail concept; but the company later relented, buying the rights and designing its own softail frame in-house.[8]

  • After 1994, the exhaust was made seamless.
  • In 1996 the master cylinder and switch gear were revised.
  • In 1999 a new 1,450 cc (88 cu in) Twin Cam engine for the 2000 model year was used. This necessitated a bespoke engine variant and changes to the frame.
  • In 2002 bullet-style indicators, alarm and immobilizer were added.[9]
  • In 2005 a 15th Anniversary version was sold, with a "Screamin' Eagle" engine, special paint and custom wheels.[9]
  • In 2006 the displacement was increased to 1,584 cc (96.7 cu in)[9] and the transmission changed six speeds.[8]
  • The 2010 "Fat Boy Lo" FLSTFB had the lowest ever Harley seat height.[2]

The 2018 Fat Boys have a redesigned softail frame with Showa front and rear suspension and new twin-counterbalanced Milwaukee-Eight engines. The two 2018 variants comprise:

  • The FLFB 1,746 cc (107 cu in) with 109 lb⋅ft (148 N⋅m), and
  • The FLFBS 1,868 cc (114 cu in) with 119 lb⋅ft (161 N⋅m)[10]

The 2018 Softail frame has a modified swingarm with a Showa rear monoshock suspension mounted beneath the seat (replacing earlier twin shocks). So as to provide a more comfortable and better controlled ride with improved handling, the front forks contain a Showa "Dual Bending Valve" (SDBV),[11] a cartridge simulator using two valves to control compression and rebound damping, giving linear damping characteristics proportional to fork stroke speed. Harley-Davidson claims the 2018 chassis is stiffer and lighter than earlier Softail and Dyna platforms.[12] Further upgrades include an LED headlight and 18-inch “Lakester” rims, with wider 160mm front and 240mm rear rubber.[13][14]

It is one of Harley-Davidson's best selling models, and has appeared prominently in a number of TV shows and movies.[3] The Fat Boy "earned a place in American pop culture" after appearances in the movie Terminator 2: Judgment Day. One of the motorcycles used in Terminator 2 is displayed at the Harley-Davidson Museum. It appeared again in Terminator Genisys.[2][15][16][17]


  1. ^ "MOTO USA". Retrieved 25 October 2016.
  2. ^ a b c "Harley Fat Boy History". Harley-Davidson. Retrieved 25 October 2016.
  3. ^ a b "Fat Boy a Harley bestseller and Hollywood favorite for 25 years". Milwaukee Wisconsin Journal Sentinel. Retrieved 28 October 2016.
  4. ^ "Vehicle Profile:25 Years of the Harley-Davidson Fat Boy". Harley-Davidson. Retrieved May 28, 2017.
  5. ^ origins of the name Fat Boy [https://itstillruns.com/harley-called-fat-boy-5167584.html}[dead link]
  6. ^ Fat Boy history [1][unreliable source?]
  7. ^ Masker, Mark. "Three decades of Softail". Hot Bike. Bonnier Corporation. Retrieved May 21, 2019.
  8. ^ a b "Harley Fat Boy Launch". Sump Magazine. Retrieved 25 October 2016.
  9. ^ a b c "Harley Fat Boy Development". Hogrides. Retrieved 25 October 2016.
  10. ^ Cameron, Kevin (August 22, 2017). "2018 Harley-Davidson Softail Cruisers Tech and Development". Cycle World. Retrieved September 17, 2017.
  11. ^ SDBV image [2]
  12. ^ "2018 Harley-Davidson Softail Cruiser Lineup". Cycle World. 2017. Retrieved September 9, 2017.
  13. ^ MacDonald, Sean (August 22, 2017). "This Is The New 2018 Harley-Davidson Softail Fat Boy". Cycle World. Retrieved July 9, 2018.
  14. ^ MacDonald, Sean (August 22, 2017). "This Is The New 2018 Harley-Davidson Softail Fat Boy". Cycle World. Retrieved July 9, 2018.
  15. ^ "'Terminator' Fat Boy preserved". Motorbike Writer. Retrieved 26 October 2016.
  16. ^ Barrett, Rick (July 22, 2015). "Fat Boy a Harley bestseller and Hollywood favorite for 25 years". The Milwaukee Journal Sentinel. Retrieved July 9, 2018.
  17. ^ Hinton, TJ (January 12, 2018). "Low Seat Height, Butt-Friendly Saddle, And A Smooth Ride". Top Speed. Retrieved July 9, 2018.