Harley-Davidson Sportster

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. The Sportster became nationally famous in the United States in 1968 with the hit TV series "Then Came Bronson", starring Michael Parks.Fact|date=January 2008

Construction

Sportster motorcycles are powered by 45 degree V-twin engines in which both connecting rods share a common crank pin. The Sportster and the 'Big Twin' side-valve motors, which were: the flathead 74 cubic-inch (1,213 cc) Models U and UH, and the 80 cubic-inch (1,311 cc) Models UL and ULH have four separate cams, sporting one lobe per cam. The OHV 'Big Twins' used a single cam with four lobes until 1999 when the 'Twin Cam' appeared, with two cams and two lobes per cam.

Incidentally, the cam followers used in the Sportsters and the side-valve W Model series were a smaller version of the followers used in the larger motors. The company used the small and large cam followers for decades with no change, from the Teens to the Eighties, probably the longest run for any engine part anywhere, in all Harley motors made those years either one or the other is called out.

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 Model K, from which the Sportster evolved, was the first civilian motorcycle produced by Harley-Davidson with hydraulic shock absorbers on both wheels. Common usage calls this a K Model.

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

Model K series

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

X series Sportsters

*XL, Ironhead, 1957–1985: 900 cc and 1000 cc Ironhead overhead-valve engines with cast iron heads
*XR750 (racing only)1970–1971: 750 cc overhead-valve engines, iron heads
*XR750 (racing only)1972–1985: 750 cc overhead-valve engines, alloy heads
*XLCR Sportster (cafe racer)1977–1978: 1000 cc overhead-valve engines, iron heads
*XR1000 (racing only)1983–1984: 1000 cc street model using XR racing cylinder head and other XR engine parts.
*XLR (racing only): 883 cc overhead-valve engines, iron heads
*XL, Evolution (known to many as the "Evo"), 1986–present: 883 cc, 1100 cc and 1200 cc Evolution overhead-valve engine, alloy heads

ignificant changes by model year

*1957 "Ironhead" overhead-valve engine introduced.
*1972 "Ironhead" 1000 cc overhead-valve engine replaces 900 cc.
*1975 Switched to left-side gear change (DOT mandate)
*1979 Only year of the sportster that harley produces with dual exhaust as opposed to staggered exhaust.
*1986 "Evolution" engine introduced in 883 cc and 1100 cc sizes.
*1988 1200 cc engine replaces 1100 cc engine.
*1991 Five-speed transmission replaces four-speed.
*1991 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. Elimination of the transmission trap door.
*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. To be released as a late '08 model.
*2007 Fuel injection replaces carburetion on all models.

Notable Sportster Models

*XLH
*XLCH
*XLCR
*XR1000
*XLH883 Hugger
*XL1200s

Nightster

Introduced in 2007, the XL1200N Nightster includes unique features such as a chopped rear fender, denim paint scheme, front fork gaiters, and a side mount license plate. The riding position and 25.3" seat height of the Nightster are the same as those of the XL883L Sportster Low.

Current models

Currently, the Sportster is offered in 8 models.In 2008, the models are:
* 883 - XL 883
* 883 Low - XL 883L
* 883 Custom - XL 883C
* 883 R - XL 883R (Brazil)
* 1200 Nighster - XL 1200N
* 1200 Low - XL 1200L
* 1200 Custom - XL 1200C
* 1200 Roadster - XL 1200R
* XR 1200 (For the moment, only european market)

Military Use

The Republic of China Military Police are using the 883 Sportster.Fact|date=January 2008

External links

* [http://victorylibrary.com/tech/XL-ratio-c.htm Model K and Sportster 4-speed transmissions examined]
* [http://www.harley-davidson.com Harley-Davidson.com]
* [http://www.xrdna.com XR1200 Prototype]
* [http://xlforum.net/vbportal/modules/Jig/index.php The Sportster Forum]
* [http://www.sportster.org The Sportster Home Page]