The idea of a four-cylinder
four-stroke was conceived way back in 1967,
when Kawasaki focused mainly on developing two-stroke motorcycles. The
decicion was made to develop a high-performance motorcycle which would
far exceed the 650W1, the largest motorcycles in Japan that time. The
goal was a fast, yet comfortable 750cc motorcycle with good handling
and brakes - a modern version of the Vincent H.R.D - Black Shadow.
Coordinated by Sam Tanegashima, a project planning group was
established and development code T103 was born.
1968 T103 mock-upThe mock-up was completed in October 1968. However,
Honda announced a new 750cc single-over-head-cam (SOHC) motorcycle at
the Tokyo Motor Show held the same year. The Kawasaki management staff
realized it was meaningless to come out with a similar model after
Honda had already introduced theirs, so all development efforts on
Kawasaki's 750cc model were stopped.
In 1970, the Z1 developing project team was reunited with the best
staff in all the fields joining the project. This group repeated
research and experiments to develop an even better bike. Kawasaki
resumed U.S. market research in March of 1970 and collected customers'
opinions from various sources such as random samplings of dealers and
editors of major motorcycle magazines. Finally, the management staff
concluded there was a strong market for a high-speed, eye-appealing
motorcycle with enough power to use as a reliable touring model.
Project T103 sketchKawasaki's
answer to this market was a 1,000cc class, four cycle, four cylinder
model. The main requirements for the Z1 engine were high speed, high
stability, and ease of dealing with pollution problems. A four cycle
unit meeting these requirements would be met by strong market demand.
The first prototype was completed in the spring of 1971. This prototype
was ridden by American test riders with minor adjustments made step by
step. In the fall of that year, the final prototype was completed and
after testing, the unit was approved for mass production. The first
production model was completed in February 1972, and this unit was
subjected to repeated severe road testing after which all parts,
including even the nuts and bolts, were examined. After reworking all
weak points, the first mass-production model was built in May 1972.
Z1 PrototypeThe 903cc displacement of the Z1 made it the largest
motorcycle in Japan. Worldwide, it was larger than Italian Moto Guzzi
850 and comparable to Harley-Davidson 1000 and 1200.
The specifications called for an air-cooled four-cycle four-cylinder
engine with a double-over-head-cam (DOHC) mechanism.
The DOHC was necessary to realize overall high performance from low
speed to high speed range. In motorcycle markets around the world,
there were only one or two other samples of this type of engine, and it
was the first engine for Kawasaki to adopt this advanced valve train.
The Z1's maximum horsepower was 82ps at 8,500rpm, 0 to 400m
acceleration was 12 seconds, and the maximum speed was above 210km/h.
The Z1 power was 8ps higher than the H2, and had great potential
considering the average horsepower of the 1,200cc automobile was 77ps
at that time. However, horsepower per displacement was comparatively
lower than the H1 and H2 because Kawasaki changed their engine design
policy so that the powerband was not set near the engine's limit,
thereby pursuing elegance and smooth engine performance. It is also
noteworthy that the Z1 engine was based on a policy to prevent
pollution and was equipped with anti-air-pollution devices such as a
positive crankcase ventilation system.
The main features of the Z1 were the reliable double-cradle steel tube
frame, a safe and reliable disc brake system, and ease of maintenance.
Since the Z1 utilized the complicated DOHC mechanism, ease of
maintenance was carefully considered at the design stage. As a result,
the Z1 could be maintained without removing the engine from the body
except for maintenance of crankshaft related parts.
The Z1 style was fresh, but cool, without the look of a 900cc heavy
weight machine. The style was achieved with tail-up mufflers, a light
tear-drop formed fuel tank, and a slim, flowing seat. All Z1 parts were
individually examined and tested time after time resulting in a five
year development period. Five years is not a short development period
for one model, although as noted earlier, development was at one time
stopped altogether. In this sense, the Z1 was the Kawasaki's flagship
model.
1972 Kawasaki Z1In September 1972, the Z1 was introduced to the U.S.
public, and sales started in November of that year. Since the
development stage, Z1 was nicknamed "The New York Steak," and the Z1
was enthusiastically welcomed by markets as the "mouth watering
motorcycle" when sales started. The suggested retail price was $1,900
and the initial sales plan called for 1,500 vehicles per month
including the European markets.
The Z1 was introduced to the Japanese public at the Tokyo Motor Show in
October of 1972 and drew the strongest attention among numerous new
models developed by our competitors.
In December 1972, Kawasaki held a press conference at Tokyo Takanawa
Prince Hotel and invited guests from 17 companies in the motorcycle
industry, and reporters from magazines and newspapers. At the
conference, a new model, the Z2, was introduced as a brother model for
the Japanese market.Production of Kawasaki's 750RS Z2 started in
January 1973. It was a 746cc machine with newly designed pistons and
crankshaft parts to express the same feeling as the Z1. The maximum Z2
horse power was 69ps at 9,000rpm with a maximum speed of 190km/h.
Let the good times roll!Sale of the Z2 started in March 1973 and were
10% higher than our competitors' 750cc class motorcycles. The 900cc
class body size and the DOHC engine attracted Japanese riders all at
once because motorcycle equipped with a DOHC engine had not existed in
Japan prior to the Z2.
During the first two years of production, Kawasaki built 80,000 Z1 and
Z2 motorcycles, and the sales of these models established Kawasaki's
reputation as a heavy weight motorcycle manufacturer.
