Harley-Davidson Sportster

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This article is about the motorcycle. For the aircraft, see ADI Sportster

Evolution Sportster cruising around downtown Buenos Aires

Harley-Davidson 45° V-twin, Sportster Evolution engine.

A typical 5-gear, foot-shift transmission on an HD Sportster

2002 Sportster 883 Custom

2007 XR1200

The Sportster is a line of motorcycles produced continuously since 1957 by the Harley-Davidson motor company. Sportster models are designated in Harley-Davidson's product code by beginning with "XL". In 1952, the predecessors to the Sportster, the Model K Sport and Sport Solo motorcycles, were introduced. These models K, KK, KH, and KHK of 1952-1956 are not always considered to be Sportsters, but are definitely the precursors and inspiration for the line.

1 Construction
2 Model K series
3 X series Sportsters
4 Significant changes by model year
5 External links

[edit] Construction

Sportster motorcycles are powered by true 45 degree V-twin engines, that is, both cylinders share a common crank pin.

Sportsters have transmissions linked to the engine with a triple-row chain primary drive and a multi-plate cable-operated clutch. 1991 and newer models have five speeds; 1990 and earlier models had four speeds.

The Sportster's motor and transmission share the same casing. The engine was mounted directly to the frame until 2004. While this system allows the bike to be somewhat lighter with more precise handling, it also transmits engine vibration directly to the rider. Sportsters released in 2004 and later use rubber isolation mounts and tie links to limit engine movement to a single plane, which greatly reduces vibration felt by the rider. Buell motorcycles built with variants of the Sportster engine have used a rubber mount system since 1987.

The Sportster was the first motorcycle produced by Harley-Davidson with hydraulic shock absorbers on both wheels.

The Sportster line of motorcycles has gone through three general stages, identified by the engine model used to power the motorcycles.

[edit] Model K series

Model K and KK 1952-1953: 750cc side-valve engines
Model KR (racing only) 1953-1969: 750cc side-valve engines
Model KH and KHK 1954-1956: 885cc side-valve engines

[edit] X series Sportsters

XL, Ironhead, 1957-1985: 900cc and 1000cc Ironhead overhead-valve engines
XR750 (racing only)1970-1971: 750cc overhead-valve engines, iron heads
XR750 (racing only)1972-1985: 750cc overhead-valve engines, alloy heads
XR1000, 1000cc street model using XR racing cylinder head and other XR engine parts.
XLR (racing only): 883cc overhead-valve engines, iron heads
XL, Evolution, 1986- present: 883cc, 1100cc and 1200cc Evolution overhead-valve engine, alloy heads

[edit] Significant changes by model year

1957 "Ironhead" overhead-valve engine introduced.
1972 "Ironhead" 1000cc overhead-valve engine replaces 900cc.
1986 "Evolution" engine introduced in 883cc and 1100cc sizes.
1988 1200cc engine replaces 1100cc engine.
1991 Five-speed transmission replaces four-speed.

Belt drive replaces chain drive on 883 Deluxe and all 1200 models.

1993 Belt drive made standard on all Sportsters.
2004 All-new frame including rubber-mounted engine for decreased vibration.
2005 Enlarged rear axle to 1" for increased stability.
2006 Helical cut transmission gears in all models reduces gear whine.
2006 New XR1200 is announced at the Intermot in Koln, Germany. The XR1200 is the first Harley-Davidson to utilize Down Draft DDFI II fuel injection. Released as a 2007 model.
2007 Fuel injection replaces carburetion on all models.
2007 The new Sportster Nighster is released. A factory 'old school chopper'-style machine.