Harley-Davidson Fat Boy

The FLFB Fat Boy with the 1745cc Milwaukee-Eight 107 sits on the new Softail frame with a concealed monoshock and rides noticeably lighter. The 107 is assigned only with 1745cc, 107 or an explicit FLFB reference, not just a year.

1,745 cc · 87 hp · 2 cyl.

The FLFBS Fat Boy 114 uses the 1868cc Milwaukee-Eight with extra torque but shares the frame and distinctive fat tyres with the 107. It is assigned only when the source contains 1868cc, 114 or FLFBS.

1,868 cc · 86 hp · 2 cyl.

The final classic Fat Boy uses the 1690cc Twin Cam 103B with clearly stronger torque. It shares the heavy, low Softail layout of its predecessors; the lighter 2018-on bikes use an all-new frame.

1,690 cc · 79 hp · 2 cyl.

The 1584cc Twin Cam 96B combines injection and a six-speed gearbox with the older Softail design. It is the step between the 1450cc 88B and 1690cc 103B and should not be treated as one broad Twin Cam row.

1,584 cc · 75 hp · 2 cyl.

The Fat Boy gained the 1450cc Twin Cam 88B with balance shafts in the classic Softail frame. Sources sometimes incorrectly list 1690cc in these years; 1450/1449cc or Twin Cam 88B is the safe identifier.

1,449 cc · 63 hp · 2 cyl.

The original FLSTF Fat Boy combines solid disc wheels with the 1340cc Evolution V-twin and classic Softail frame. This is the recognisable carburetted generation; a later Twin Cam is not a mechanical evolution of the same engine.

1,340 cc · 57 hp · 2 cyl.