Kawasaki ZX-6R

The Kawasaki Ninja ZX-6R is a Kawasaki middleweight sport bike. It was introduced in 1995 and has been constantly updated throughout the years in response to new products from Honda, Suzuki, and Yamaha. The ZX series is what was known as the Ninja line of Kawasaki motorcycles in the 1980s and still carries the moniker in North America today.

When Kawasaki introduced the ZX-6R in 1995, it was the first middleweight sport bike, since the 1992 GSXR600 with an aluminum frame. It had a dry weight of 401.2 lb (182.0 kg), wet weight of 454 lb (206 kg), and was capable of accelerating 0-60 mph (97 km/h) in only 3.6 seconds.

1997 Kawasaki Ninja ZX-6R
With competition from Honda's CBR600F4i, Suzuki's GSX-R600, and Yamaha's YZF-R6 getting more aggressive, Kawasaki decided to make an unusual move for the 2002 model year. They increased the capacity of the traditional 600 cc (37 cu in) motor to 636 cc (38.8 cu in). For riders who needed bikes for displacement-restricted racing, Kawasaki also made available a limited production 599 cc (36.6 cu in) version called the Ninja ZX-6RR, but the 636 cc (38.8 cu in) ZX-6R would be their main mass production middleweight sport bike.

2002 Kawasaki Ninja ZX-6R
2003 brought many new changes to the ZX-6R, or ZX636 as it is often referred. The engine was now fuel injected and engine speed was raised around 500 rpm which resulted in a slight gain in power. Radial-mounted 4-piston brakes replaced the previous 6-piston brakes and the front forks were now inverted. Chassis improvements resulted in higher rigidity and less weight. An all digital instrument panel was also introduced and a larger ram air inlet moved to the center over the headlight, running through the headstock. The bike carried over to the 2004 model year with just color scheme changes. The ZX-6RR won the Supersport category award for Masterbike 2004 and placed 3rd overall. MSRP for the 2003/2004 models was $7999 USD.

2005 Kawasaki Ninja ZX-6R
In 2005, Kawasaki again revamped the ZX-6R. Engine speed increased again by 1,000 rpm resulting in 105 hp (78 kW) at 12,250 rpm. The frame and swingarm were updated, but the main changes from its predecessor lay in the design. The aluminum frame was now painted flat black, fairings were more round, and integrated turn signals were used (euro model). The exhaust was now centrically under the seat (a configuration commonly referred to as an undertail exhaust). Most of these changes were mirrored in the 599 cc ZX-6RR. For the second year in a row, the ZX-6RR again won the Supersport category award for Masterbike 2005 and placed 3rd overall. The bike carried over to the 2006 model year with minor suspension changes and new color schemes. The 2005/2006 ZX-6Rs had an increased MSRP of $8,699 USD.


2007 Kawasaki Ninja ZX-6R
After four years of offering their 636 cc ZX-6R for street use and an entirely separate 599 cc ZX-6RR for displacement-restricted racing classes, Kawasaki offers only one ZX-6R for 2007, and it displaces 599 cc. Previous years of the ZX-6R's engines were all built from the same basic design, but the all-new engine for 2007 was redesigned from the crankcase up. In following with what their competitors had already been doing, Kawasaki's new engine features a stacked gear arrangement in which the crankshaft, primary drive and countershaft are placed in a triangular format for a shorter, more compact powerplant. It's now about 40 mm smaller in both length and width, said to yield greater cornering clearance. By using a former 125 cc Grand Prix racer as the ZX-6R’s chief development rider, Tomomi Manako, Kawasaki claims a focus has been put on track usage. Frame, swingarm, suspension, brakes, and body are completely redesigned and the bike shares very few parts from the previous model. MSRP was increased to $8,999 USD and the ZX-6R expected to carry over to the 2008 model year with just color scheme changes.

source: http://www.wikipedia.org/

Kawasaki Ninja ZX-10R

The Kawasaki Ninja ZX-10R is Kawasaki's follow-up to the ZX-9R sport bike. It was originally released in 2004 with minor revisions in 2005, it combines ultra-narrow chassis, low weight, radial brakes, and strong engine make it a very competitive package for its Japanese rivals: Suzuki's GSX-R 1000, Honda's CBR1000RR and Yamaha Motor Company's R1. In 2004 and 2005 the ZX-10R won Best Superbike from Cycle World magazine and the prestigious international Masterbike competition. It is known to be the most 'hard edged' or race oriented out of the Japanese one-liter inline four cylinder motorcycles, with relatively quick steering and a ferocious powerband.
A complete overhaul to the ZX-10R in 2006 sees the most comprehensive round of changes since the bike was introduced.
The 2008 model has an MSRP of USD $11,549.

Engine
Kawasaki engineers utilized a "stack" design for a liquid-cooled, 998 cc inline four-cylinder engine. The crank axis, input shaft and output shaft of the "Ninja" ZX-10R engine are positioned in a triangular layout to reduce engine length, while the high-speed generator is placed behind the cylinder bank to reduce engine width. With a bore and stroke of 76 x 55 mm, the ZX-10R engine's one-piece cylinder and crankcase assembly reduces weight and increases rigidity. The DOHC are machined from chromoly steel billet for strength, four valves per cylinder improve high-rpm breathing, and the forged, lightweight pistons offer high heat resistance to further enhance the bike's power-to-weight ratio.

Cooling System
In addition to liquid cooling, the ZX-10R engine features an oil cooler adjacent to the oil filter to reduce oil temperatures. "Slosh" analysis was also used to design the internal structure of the oil pan, thereby reducing windage losses and helping to maintain low oil temperatures. The radiator is provided by Denso and helps reduce weight.

Clutch
A multi-plate wet clutch with a back torque limiter transfers power to a six-speed, close-ratio transmission ideal for closed-course competition. The back-torque limiter automatically disengages the clutch under hard braking and deceleration to prevent rear wheel hop during corner entry, commonly known as "backing it in" (looks good when done correctly). This also ensures complete control under hard braking.

Wheels
A new six spoke wheel design is claimed to be almost as light as special purpose race wheels. The sidewall profile of the rear tire has been increased from 190/50/ZR17 to 190/55/ZR17.


The 2006 ZX1000D6F model carried over to the 2007 model year, with only color scheme changes. The most noticeable difference between 2006 and 2007, is that the heat-shields on the exhaust pipes are black on the '07 ZX10R, and '06 came with silver ones. The ZX-10R is expected to be all new for the 2008 model year.

Specifications
Engine Type: 4-Stroke, 4-Cylinder, Liquid-Cooled, DOHC, 4 Valve Cylinder Head
Displacement: 998 cc
Bore & Stroke 76.0 x 55.0 mm
Maximum Torque: 84.6 ft·lbf @9500 rpm
Compression Ratio: 12.7:1
Fuel Injection: DFI with Mikuni 43 mm Throttle Bodies (4)
Ignition: TCBI with Digital Advance
Transmission: 6-Speed
Final Drive: X-Ring Chain
Rake/Trail: 24 degrees/4.0 in.
Front Wheel Travel: 4.7 in
Rear Wheel Travel: 4.9 in.
Front Tire Size: 120/70 ZR17
Rear Tire Size: 190/55 ZR17
Wheelbase: 54.7
Front Suspension: 43 mm Inverted Cartridge Fork with Adjustable
Preload, Stepless Rebound and Compression Damping
Rear Suspension: Uni-Trak with Adjustable Preload, Stepless
Rebound and Compression Damping, Ride Height
Front Brake Type: Dual Floating 300 mm Petal Discs with
4-Piston Radial-Mount Calipers
Rear Brake Type: Single 220 mm Petal Disc
Fuel Tank Capacity: 4.5 gal
Seat Height: 32.5
Dry Weight: 386 pounds (175 kilograms)
Color: Lime Green/Flat Sonic Black, Ebony, Pearl Solar Yellow, Hydro Blue

source: http://www.wikipedia.org/

Kawasaki Ninja 250R

The Kawasaki Ninja 250R is a street motorcycle sold by the Kawasaki Motors division of Kawasaki Heavy Industries since 1983. It is Kawasaki's best-selling motorcycle, experiencing steady double-digit sales growth year after year. It is renowned for its light handling, good fuel economy, sufficient power, and relatively comfortable riding posture, making it a desirable first motorcycle for new riders, and a popular machine with experienced riders who seek a second machine, or wish to enter the sportbike category. The smallest Ninja has undergone few changes throughout its quarter-century existence, having seen only two substantial redesigns.

Nomenclature
Owners and fans of the motorcycle commonly refer to it by its platform designation, EX250. This designation is followed by an alphabetical suffix indicating the generation. Before the 2008 model, the motorcycle carried different marketing names worldwide/ The 2008 (EX250-J) model is known as the Ninja 250R in all markets. In the United States, previous generations (EX-250E/F/G/H) were also marketed as members of the "Ninja" family of sportbikes, while outside the U.S. it is known as the ZZR-250, ZX-250, or as the GPX-250R. Past models (EX250-C) have carried the base designation GPZ-250. As the smallest of the Ninja motorcycles, the Ninja 250R has received the affectionate nickname "Ninjette" or "Baby Ninja".

Description and features
In many respects, including ergonomics, chassis design, engine placement within the frame, the Ninja 250R straddles standard and sport classes. Likewise, the bike's riding position falls between standard and sport. Capable of running the 1/4 mile in 14.6 seconds at 88mph, the bike's features include bungee hooks, center stand (no longer available on the 2008 model), a tachometer, and front and rear disc brakes. The bike has been heavily updated for 2008 with completely redesigned fairings and 17" wheels. As of 2007, the 250R is being produced in Thailand. Kawasaki has marketed the Ninja 250R since 1986 as an entry-level. The Ninja 250 has little direct competition within its class in the United States, partly due to it being one of the two 250 cc sport bikes sold. In Canada, Honda's 2007 introduction of the CBR125R has caused competition for Kawasaki's share in the entry-level sport bike market. The other main competitors are the other 250 cc "beginner bikes," namely the Hyosung GT250R, Honda's Rebel 250 and Nighthawk 250, the Suzuki GZ250, and the Yamaha Virago 250. With the exception of the Nighthawk, (a standard) and the Hyosung, these bikes are all cruisers.
Before the 2008 model, neither the Ninja nor these other US 250's had changed much in recent years, but outside the United States there were many advances in small-displacement, lightweight, and/or low-cost motorcycles, including several four-cylinder, sixteen-valve 250s (e.g., the Honda "Hornet" 250 or Ninja ZX-2R). That being said, the Ninja 250 enjoys a modest following among riders who appreciate its light weight and nimble handling as an amusing "track bike." The very fact that it hasn't changed much since 1988 means parts are plentiful and inexpensive, and the rider community is well established.

First generation
EX250-C - Also known as the GPZ-250. This earliest, belt-driven version was first produced in 1983, and has nothing in common with the latest generation.

Second generation
EX250-E - This model was sold as the Ninja 250R in Canada and the U.S. between 1986 and 1987. It was known as the GPZ-250R elsewhere. The engine from this model persisted until 2007 with minimal changes.

Third generation
EX250-F - The most widespread version of the motorcycle, it was sold between 1988 and 2007 in the U.S.. Canada received the model between 1988 and 1999, and it was available elsewhere as the GPX-250R as early as 1987.
EX250-G - Never sold in North America, this version was known as the GPX-250R-II. It sported dual front brakes, which slowed a wider wheel and tire (110/80-16). All other parts where identical to the -F model. It was sold after 1988.
EX250-H - This model came to Canada as the Ninja 250R between 2000 and 2001, after which it received a new name: ZZR-250, in line with the -H model's name elsewhere in the world, where it had existed since 1992. This motorcycle has few parts in common with the -F model, though it shares the same engine (with different casings). It sports a lateral aluminum frame, different fairing (designed to make it look sportier), larger (17") wheels, an adjustable rear shock absorber, adjustable brake and clutch levers, a smaller drive sprocket, computer-controlled timing advance, and a revised electrical system.

Fourth generation
In 2008, Kawasaki gave the EX250 its most thorough modernization in many years. The EX250-J model is known as the Ninja 250R worldwide. Kawasaki increased the MSRP by $500 U.S.D., to $3,499 in 2008 and by $1,000 U.S.D. to $3,999 in 2009.
Parts from the third generation are still found on the -J, but its redesigned exterior panels bring the smallest Ninja's appearance out of the '90s and into line with late-2000s sportbikes. The engine and drivetrain retain 30% of the -F model's parts, according to Kawasaki literature. The engine's compression and maximum torque have been lowered to provide 20% better midrange performance, where the motorcycle will spend most of its time. The U.S.-spec -J model uses dual carburetors like the -F model, but the European-spec and Thailand-spec model have a fuel-injection system. The wheels were increased in size to 17", the front suspension was beefed up, and the front brake rotors were replaced with a larger "petal" design. A fuel gauge, a rarity in motorcycles, was added to the instrument cluster, implying an emphasis on attracting new riders.

Motorsports
Since the introduction of the model in 1986, the Ninja 250 has been often used as a "starting class" bike in club racing around the world. The AFM in California has been especially involved with 250 Production racing since the bike was released, including the since faded Honda VTR250.
In 2007 (the last year of the 3rd generation EX250), the Ninja 250 of Hambone Racing, won the Overall Mini Endurance Championship with the Central Motorcycle Roadracing Association (CMRA). Piloted by CMRA longtimers Chuck Ergle and Keith Hertell, this marked the only time a Ninja 250 had ever won a CMRA Mini Endurance Championship.
Starting in 2008, the WSMC will have a class (The Ninja Cup) dedicated to the model.

source: http://www.wikipedia.org/

Honda CBR150R

The Honda CBR150R is a 150cc 4-stroke sports bike which is a part of the Honda CBR series manufactured by APHonda. APHonda is a Thai owned, established 1986, company. APHonda is a Honda affiliate company. Built as the successor of the 2-stroke Honda NSR 150, the CBR150R is targeted mainly to Southeast Asia. Officially launched into Malaysian market in December 2007 with two color choices offered, red and blue. Black color is available in other country like Thailand,Japan or Indonesia market.

Features
DOHC 4-valve 150 cc water-cooled engine with balancer shaft.
6-speed return manual transmission
Front and rear(Nissin disk brake) disc brakes.
Key slot cover for better protection against theft (2006 onwards).
Monoshock rear shock absorber.
Secondary Air Supply System (SASS) which delivers extra air to the exhaust system for cleaner emission.
Catalytic converter

Instrument Panel
This bike uses analog instrument panel which consist of fuel meter, speedometer, revolution per minute meter, temperature meter and signal, high beam and gear status light indicator.

Honda CBR1000RR Fireblade

The CBR1000RR (also known as the Fireblade) is a 999 cc (60.9 cu in) liquid-cooled inline four-cylinder Honda sport bike that was introduced in 2004 to replace the CBR954RR

Racing roots
The Honda CBR1000RR was developed by the same team that was behind the Honda RC211V race bike for the MotoGP series. Many of the new technologies introduced in the Honda CBR600RR, a direct descendant of the RC211V, were used in the new CBR1000RR such as a lengthy swingarm, Unit Pro-Link rear suspension, and Dual Stage Fuel Injection System (DSFI).

2004
The Honda CBR1000RR was the successor to the CBR954RR. While evolving the CBR954RR design, few parts were carried over to the CBR1000RR. The compact 998 cc (60.9 cu in) in-line four was a completely fresh design, with unique bore and stroke dimensions, race-inspired cassette-type six-speed gearbox, all-new ECU-controlled ram-air system, dual-stage fuel injection, and center-up exhaust featuring a new computer-controlled butterfly valve. The chassis was likewise all new, including an organic-style aluminum frame composed of Gravity Die-Cast main sections and Fine Die-Cast steering head structure, inverted fork, Unit Pro-Link rear suspension, radial-mounted front brakes, and a centrally-located fuel tank hidden under a faux cover. Additionally, the Honda Electronic Steering Damper (HESD) debuted as an industry first system which drastically improved stability and nearly completely eliminated head shake while automatically adjusting for high and low speed steering effort.
A longer swingarm acted as a longer lever arm in the rear suspension for superior traction under acceleration and more progressive suspension action. Substantially longer than the corresponding unit on the CBR954RR (585 mm (23 in) compared to 551 mm (21.7 in)) the CBR1000RR's 34 mm (1.3 in) longer swingarm made up 41.6 percent of its total wheelbase. The CBR1000RR's wheelbase also increased, measuring 1405 mm (55.3 in); a 5 mm (0.2 in) increase over the 954.
Providing room for a longer swingarm required massive changes to the engine architecture, another reason the CBR1000RR power plant shares nothing with the 954. Shortening the engine compared to the 954 meant rejecting the conventional in-line layout. Instead, engineers positioned the CBR1000RR's crankshaft, main shaft and countershaft in a triangulated configuration, with the countershaft located below the main shaft, dramatically shortening the engine front to back, and moving the swingarm pivot closer to the crankshaft. This configuration was first successfully introduced by Yamaha with the Yamaha YZF-R1 model in 1998 and inspired superbike design in the following years to date.

2004 CBR1000RR
Positioning this compact engine farther forward in the chassis also increased front-end weight bias, an effective method of making high-powered liter bikes less wheelie prone under hard acceleration. This approach, however, also provided very little space between the engine and front wheel for a large radiator. Engineers solved this problem by giving the RR a modest cylinder incline of 28 degrees, and moving the oil filter from its frontal placement on the 954 to the right side of the 1000RR engine. This allowed the RR's center-up exhaust system to tuck closely to the engine, opening the space required for a massive MotoGP-style curved radiator with 40 percent more cooling capacity than the 954's unit, a key to making big horsepower with high durability.
The engine was designed specifically with an eye toward handling as well as horsepower and torque. Since the power plant represents a large percentage of a motorcycle's mass, the engine must be configured to assist the handling process, not hinder it. For decades, Honda has championed the concept of mass centralization, that is, concentrating the component masses as close to the motorcycle's center as possible. The CBR1000RR elevated that concept to a higher plane.
Honda engine designers paid special attention to making the CBR1000RR power plant an extremely compact package to enhance mass centralization and reduce the roll polar moment, while yielding other benefits as well. While some engines employ ever-more oversquare dimensions, Honda employed a relatively modest 75 mm bore with a 56.5 mm (2.2 in) stroke to derive a displacement of 998 mm (39.3 in). This choice yields a remarkably narrow engine fit into a commensurately narrower chassis, all the better for increased mass centralization and improved ground clearance as well.
Other measures taken to enhance mass centralization in the CBR1000RR included positioning the starter motor and drive gear on the right side of the engine, which also created a narrower engine profile for added ground clearance. The 1000RR incorporated a balancer shaft to virtually eliminate secondary engine vibration, and with an eye toward mass centralization it too has been positioned close to the engine's center of gravity. Placing other major masses (fuel and rider) closer to the roll axis resulted in a motorcycle that reacted more quickly and smoothly to control inputs at the handlebars. Like the RC211V and the CBR600RR, the CBR1000RR fuel tank shares space under a faux tank cover with a forward-mounted air box, thanks to the Unit Pro-Link rear suspension system.
The Unit Pro-Link design provided a wealth of benefits. The shock is contained entirely within the swingarm and is positioned lower than in a conventional design. Both contribute to mass centralization, in part by giving the centrally mounted fuel tank room to extend downward. Because the shock is contained within the swingarm and does not require a top mount on the frame, the bulk of the 4.8-gallon tank was positioned down low between the frame rails, close to the centerline of the machine. Two other benefits resulted from the RR's fuel placement; the mass of the fuel load has less effect on handling, thereby facilitating quick directional changes; and, because the fuel tank is shorter, the CBR1000RR rider sits closer to the steering head compared to the 954.
To achieve quicker handling, Honda engineers also lightened as many pieces as possible that are far from the center of mass. That gave rise to the RR's compact Line-Beam headlights, with their high-illumination three-piece reflectors; slim-line LED taillight; single-piston rear brake system that's lighter than that of the 954; an analog/digital fully electronic instrument panel that's one of the lightest and slimmest ever mounted on a street bike; plus a host of other changes.
The 2004 model carried over to the 2005 model year with only color scheme changes.

2007 Honda CBR1000RR
The 2006 CBR1000RR offered incremental advancements over the earlier model with more power, better handling and less weight. Changes for 2006 include:
New intake and exhaust porting
Higher compression ratio
Revised cam timing
More intake valve lift
Double springs for the intake valves
Higher redline
Larger rear sprocket
New exhaust system
New chassis geometry
Larger 320 mm (12.6 in) front brake discs but thinner at 4.5 mm (0.2 in)
Revised front suspension
Revised rear suspension with new linkage ratios
New lighter swingarm
Revised front fairing design
The 2006 model carried over to the 2007 model year mostly unchanged. The brushed aluminum swingarm was changed to black and the bike is offered in four new color schemes; Black, Red/Black, Satin Silver and Race-Replica Repsol.

2008
An all new CBR1000RR was introduced at the Paris International Motorcycle Show on 28 September, 2007 for the 2008 model year. The CBR1000RR is powered by an all new 999 cc (60.9 cu in) inline-four engine with a redline of 13,000 rpm. It features titanium valves and an enlarged bore with a corresponding reduced stroke. The engine has a completely new cylinder block, head configuration, and crankcase with lighter pistons. A new ECU delivers two separate revised maps sending the fuel and air mixture to be squeezed tight by the 12.3:1 compression ratio. Ram air is fed to an enlarged air box through two revised front scoops located under the headlamps. Honda claims power output to be at least 178 hp (133 kW) beginning at 12,000 rpm.
Honda made a very focused effort to reduce and centralize overall weight. A lighter, narrower die cast frame was formed using a new technique which Honda claims allows for very thin wall construction and only four castings to be welded together. Almost every part of the new bike was reengineered to reduce weight including the sidestand, front brake hoses, brake rotors, battery, and wheels.
In order to improve stability under deceleration, a slipper clutch is now available with a unique center-cam-assist mechanism. The Honda Electronic Steering Damper (HESD) has been revised this year as well. Another significant change is the exhaust system which is no longer a center-up underseat design. The CBR1000RR now features a side slung exhaust in order to increase mass centralization and compactness while mimicking a Moto GP style.

2009
On the 5th of September 2008 Honda released details of the 2009 model. The bike remained the same, in terms of engine, styling and performance. However as a factory fitted optional extra the addition of Combined ABS "C-ABS" has been introduced.

Competition
For the 2008 model year, the CBR1000RR competes with the Suzuki GSXR1000, the Yamaha YZF-R1, the Kawasaki Ninja ZX-10R, and the Ducati 1098. The CBR1000RR is consistently winning comparison shootouts performed by major and minor motorcycle media publications

source: http://www.wikipedia.org/

APRILIA RS-125

The Aprilia RS125 is a GP derived replica sport production motorcycle. It is powered by a single cylinder 2-stroke, Nikasil coated aluminium cylinder block, liquid cooled 124.8 cc Rotax engine.
Aprilia has had many Grand Prix victories in the 125 cc and 250 cc 2-stroke classes. With years of racing experience, Aprilia has released a new version of the RS125 with new looks, performance & styling.
Key features of the new Aprilia RS125 are: New frame technologies that promise superb agility and are much lighter than previous model. Combined with new frame structure and material the frame is a re-creation of the one used on the Aprilia GP125 racing bike. New racing wheels with Y-spoke configuration make the rim lightweight while retaining high strength. They are made from a die cast moulding process which reduces unsprung weight and guarantees rigidity under racing conditions.

Generations

RS125R Extrema 1992 to 1995
Aprilia introduced the first RS125 in 1992. It has the distinctive features of having an angular tail section and swept front fairing, square cut headlight unit, three spoke rims,air scoops on the upper front middle fairing, kick start on the left hand side and analogue gauges.

RS125 1996 to 1998
The RS125 is revised and the R prefix is dropped. The RS retains a lot of the appearances of the previous RS but there are some notable differences. The front air intakes are integrated into the front upper portion of the middle fairing. The headlight unit is rounded and the lip is introduced to the top centre. A digital gauge is added in place of the temperature gauge.

RS125 1999 to 2005
The RS125 is revised again in 1999 with more rounder and bulbous fairings, five spoke rims and a single air duct on the right hand side. The lip on the headlight unit is increased in size.

RS125 2006 onwards
The RS125 was given completely new fairing styling similar to the RSVR. The most notable features are the angular fairings, two headlight units, digital gauge and multispoke rims.

Tuono 1999 to 2005
The RS125 Tuono was introduced in 1999 as a semi naked version of the RS125. Production ran until 2005 and was subsequently dropped from the line-up.
The Tuono was essentially an RS125 with the middle and lower portions of the fairings absent and a handlebar fitted on the top yoke.

Race replica colour schemes
Throughout the history of the RS125, various race replica colour schemes and tributes of various racers have been available, from Haga, Harada, Rossi, Poggali.

source: http://www.wikipedia.org/

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.

Construction

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

2002 Sportster 883 Custom
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

Significant changes by model year:
2001 883 Sportster Hugger
2007 XR1200 Prototype
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.
1985 Last year for the "Ironhead" overhead-valve engine.
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
2002 Sportster Custom 883
XLCH
XLCR
XR1000
XLH883 Hugger
XL883C and XL1200C Custom -both these models have a 21" front laced and 16" solid disk rear wheels
XL1200S Sport -this Sportster has adjustable suspension, two front disc brakes and hotter cams
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 Nightster - XL 1200N
1200 Low - XL 1200L
1200 Custom - XL 1200C
1200 Roadster - XL 1200R
XR 1200

source: http://www.wikipedia.org/