1972 Kawasaki Z1
|Manufacturer||Kawasaki Heavy Industries, Ltd.|
|Also called||Kawasaki 900 Super Four |
|Production||1972—1975; 85,000 units (est.) |
|Successor||Kawasaki Z900 |
|Class||Standard (muscle bike)|
|Engine||DOHC 903 cm3 (55.1 cu in) air-cooled, inline-four |
|Bore / stroke||66 mm × 66 mm (2.6 in × 2.6 in)|
|Top speed||130 mph (210 km/h) |
|Power||82 PS (81 hp) at 8500 rpm |
|Torque||54.2 lb·ft (73.5 N·m) at 8500 rpm |
|Frame type||Full duplex cradle|
|Suspension||F: Telescopic, R: Swing arm|
|Brakes||F: 11.5 in (290 mm) disk (optional 2nd disk)
R: 7.9 in (200 mm) drum, leading trailing 
|Tires||F: 3.25-19, R: 4.00-18|
|Wheelbase||1,490 mm (59 in)|
|Dimensions||L: 2,200 mm (87 in)
W: 685 mm (27.0 in)
H: 1,170 mm (46 in)
|Weight||230 kg (510 lb)  (dry)
542 lb (246 kg)  (wet)
|Fuel capacity||18 L (4.0 imp gal; 4.8 US gal)|
The Kawasaki Z1 was a motorcycle introduced in 1972 by Kawasaki. The Z1, along with Honda's CB750 from 1969, introduced the four-cylinder, across the frame, disc-braked layout to a wider public. The Z1 was groundbreaking in that it combined many different elements which previous motorcycles had used into one performance package. The names differed in some countries as Z900, 900 Z1 or 900 S4 ("Super Four"). It was the first of a long and still ongoing series of Kawasaki Z models.
The Kawasaki Z1 was developed in strict secrecy under the project name "New York Steak". In the late 1960s Kawasaki, already an established manufacturer of two-stroke motorcycles, decided to make a 750 cc four-cylinder four-stroke sports motorcycle (they even had an appearance prototype designed by McFarlane Design in 1969), but they were beaten to the marketplace by the Honda CB750. This postponed the Z1's release until its displacement could be upped to 903 cc and sold as a 1000cc-class machine.
Production began in 1972; at the time it was the most powerful Japanese 4-cylinder 4-stroke ever built. The Z1 had full instrumentation and an electric start, produced 82 bhp and had a maximum speed of 130 mph (210 km/hr). It met with very positive reviews from the motorcycle press, who praised its smoothness, damped vibration, easy-starting (kick-start and electric were both available), straight-line stability and linear acceleration. Steering was accurate and the bike handled well, but testers said the rear tire, chain and rear shocks all wore out quickly.
The Z1 was awarded the MCN 'Machine of the Year' accolade for four years running between 1973 to 1976 (an award resulting from a readers' opinion-poll run by UK weekly publication Motorcycle News) The Society of Automotive Engineers of Japan (Japanese) includes the 1972 Z1 as one of their 240 Landmarks of Japanese Automotive Technology.
The basic design of the Z1 remained relatively unchanged until 1975, when the 903 cc "Z1-B" was introduced, with changes including power output, improved suspension, a stiffer frame, deleted automatic chain oiler, revised styling (essentially paint scheme and side cover nomenclature), and improved braking.
In 1976 the Z1 was replaced by the Kawasaki KZ900, called Z900 in some countries. This was succeeded by the 1977 Kawasaki Kz1000 ("Z1000") and Kawasaki Z1000 Z1-R, and in 1984 by the Kawasaki Z1100R.
In 1983, Kawasaki won back the crown of the fastest production bike with the Kawasaki GPZ900R which had some other references to its predecessor like the model designation code ZX900, four cylinders and 900 ccm.
- "Kawasaki 900 Super Four". 240 Landmarks of Japanese Automotive Technology. Society of Automotive Engineers of Japan, Inc. Retrieved 6 November 2013. "Journalists and riders called it the king of motorcycles, and it gained a reputation as a super sport model all over the world. The Super Four boasted high performance and quality. This best-selling motorcycle won many prizes around the world within only six months of its release."
- Siegal, Margie. "1973 Kawasaki Z1: King of the Road". Motorcycle Classics May/June 2006. Motorcycle Classics. Retrieved 10 December 2012.
- Ker, Rod (29 September 2008). "Kawasaki Z1: remembrance of things fast". The Telegraph. Retrieved 6 November 2013. "While I don't have a clue what I was doing when Kennedy was shot, I can clearly remember the first time I saw a Kawasaki Z1. In 1974, this four-cylinder, 903cc, 81bhp, 132mph projectile was the fastest, most glamorous thing on two wheels. Only a handful had been sold in Britain, and only the lucky few had even seen one."
- Newland, Martin (5 May 2004). "Retro rocket". The Telegraph. Retrieved 6 November 2013. "The 1973 Kawazaki Z1 was the world's first superbike and its spiritual successor, the Z1000, relies on the same stripped-down looks and raw, steady power for its appeal. It's the ideal big boy's toy…"
- Walker, Mick. Motorcycle: Evolution, Design, Passion. The Johns Hopkins University Press. p. 150. ISBN 978-0-8018-8530-3.
- Williams, Greg. "Son of Z1: The 1976 Kawasaki Z900". Motorcycle Classics September/October 2012. Motorcycle Classics. Retrieved 10 December 2012.
- John L. Stein (1 August 2010). "Then & Now: Kawasaki Z1000 vs. Z1". Motorcyclist Online. Source Interlink Media. Retrieved 6 November 2013. "During its development, the 1973 Kawasaki Z1 was codenamed New York Steak. And it was just that: 23 percent larger than Honda's benchmark 750cc Four, it busted open the fledgling superbike ranks and would soon make its impact in racing, too. Blasphemously heavy at 542 lbs. wet, the Z1 did everything to excess, from its audacious 903cc DOHC four-cylinder engine to its roomy cockpit, enormous linkless chain with proprietary oil pump, and quartet of chrome-plated megaphones."
- Melling, Frank (27 July 2007). "Memorable Motorcycle Kawasaki Z1". Motorcycle USA. Retrieved 6 November 2013. "It's time to correct one of the popular myths which is becoming ever more prevalent in the motorcycling world. Thus: 'When Honda launched its 750 '4' in 1968, the biking world fell on its knees and worshipped the new arrival.'"
- Kuhn, Fran (24 February 2009). "Kawasaki 903 Z1 - Bikes of the 70's". Motorcyclist Online. Source Interlink Media. Retrieved 6 November 2013. "By now you must've already heard the story of how the Z1--code-named 'New York Steak' for some ridiculous reason or other by Kawasaki--was originally intended to be a 750, and of how Kawasaki brass nearly suffered a corporate coronary when Honda introduced its own 750cc four-cylinder in late 1968. Kawasaki, cornered, had no choice but to make the Z1 even bigger and stronger and tricker than the mighty CB750."
- "40 years of Kawasaki's 'Z' sleds". Independent Online. Independent Newspapers (Pty) Limited. 5 June 2012. Retrieved 6 November 2013. "…the DNA of the 1972 Z1 is still clearly discernable in the Kawasaki's current litre-class musclebike, the Z1000."
- "The Kawasaki Prototype". Motorcycle Classics September/October 2006. Motorcycle Classics. Retrieved 10 December 2012.
- "Kawasaki official site". Retrieved 2013-04-06.
- Wagar, Ivan. Kawasaki's 900cc New York Steak, Cycle World October 1972.
- Kawasaki 900 Z-1 Road Test, Cycle World March 1973.
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