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[Phantom Motorcycle] Kawasaki 2 Stroke Monster, SQUARE- FOUR 750 (Tartar Steak)


There were a few machines that had disappeared in the middle of development without going out into the world and it rarely comes down to the table. They would like to take a look at such a visionary vehicles like this.

Let’s introduce Kawasaki’s SQUARE-FOUR 750 this time.

Abandonment development due to regulation of exhaust gas in the USA

Although Kawasaki aimed at the fastest seat in the world with Mach 3 of 2 st parallel 3 cylinder 500cc in 1969, Honda’s CB 750 FOUR which appeared at the same time was standing in front of me.

In order to defeat it, in October 1971, Mach 2 of 750cc of two-stroke parallel 3 cylinders was released. It nominates the highest speed 203 km / h, taking the world’s fastest. In the autumn of the following year, 900SUPER FOUR = Z1 of four-stroke parallel four-cylinder was also released, and Kawasaki made the world’s fastest seat immovable in a blink of an eye.

Meanwhile, behind the development of the four-stroke Z1 that emerged as a protagonist of the era, there were technicians who struggled to develop with two strokes, and it was this SQUARE-FOUR 750 that was almost completed until its completion.

Unfortunately the development was canceled in August 1973 due to the influence of the regulations of the US emissions regulations. If it was on sale it would have been a machine beyond Z1 … ….

[KAWASAKI SQUARE – FOUR 750 1973] Adopted 750cc water cooled square 4 engine ahead of RG 500 Γ (1985) that came out afterwards. It is a phantom model developed by Mr. Hiroyuki Matsumoto (deceased) who is the creator of Mach as a successor to the parallel 3-cylinder series.

This is SQUARE – FOUR 750 taken at the Kawasaki Motorcycle Fair held in February 2017.

Although the maximum output was not announced, August 1973 when it was canceled as development was already the time Z1 was on sale, it probably had been in range.

By the way, Mach 4 of the second strike 3 cylinder 750 cc was 74 ps.

Development code “0280” was called Tartar steak

Always aiming for “the world’s fastest”, Kawasaki got the title of the fastest commercial motorcycle in the 750 SS (Mach IV) of air-cooled 2 cycle 3 cylinder that appeared in 1971.

But power competition intensified due to market needs.

SQUARE-FOUR that code number “0280” was secretly started to develop, while further improvement in performance is required.

Kawasaki’s development team aimed to exceed Mach with its maximum speed and machine integrity, leaving the 750 SS displacement and maximum power.

It was a new challenge to pursue the performance of the entire motorcycle instead of relying on acceleration performance and maximum speed only for power.

The engine employs a compact layout of the water-cooled square 4 in order to suppress the air resistance of the front part, and integrates the right front-rear cylinder and the left front-rear cylinder. Twin carburetor specifications with suction ports connected to each, and fuel injection was also developed accordingly.

The 2 in 1 exhaust pipe designed with priority to the design has made two independent on the inside to prevent power down.

Development has progressed steadily, and it approached a little more to achieve the target figure, but in August 1973 the plan stopped due to the influence of the regulations of the US emission regulations.

Ultra high-performance machine SQUARE-FOUR called the common name “tartar steak” in the company became a phantom model without seeing the sunlight.

*From the display panel of Kawasaki

Adopting a cylinder that integrates the front and rear cylinders on the left and right, it has twin carburetor specifications one on each side.

It was explained that it did not make it into 4 parallel cylinders by the flow from Mach to suppress the full width.

Mr. Matsumoto revealed that he was also developing the FI specification at the time of past interviews, but the matter was also listed on the display panel of Kawasaki.

It is unique that it is set to square = square shape according to the engine of square 4 or meter design.

Since it is water-cooled, a water temperature gauge is arranged at the center. Kawasaki’s first water-cooled model will be on sale until about 1979 model Z 1300 in about 6 years.

In 1973 the Mach series at that time was a kick start, but you can see things that seem to be cell motors under the engine.

Since the kick pedal also exists on the right side of the engine, it probably was a cell / kick combination formula.

Original Source[ YOUNG MACHINE(*Japanese) ]

See KAWASAKI Moto Index Page



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