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Tuesday, October 10, 2023

Yamaha's Hidden Gem: The RZ201 Rotary Engine Motorcycle

Hidden GEM - Yamaha, the renowned Japanese motorcycle manufacturer, is synonymous with exotic designs and powerful performance. However, in the early 1970s, Yamaha ventured into uncharted territory by secretly developing a motorcycle equipped with a Rotary/Wankel engine, known as the Yamaha RZ201.
Yamaha RZ201 debuted at the Tokyo Motor Show 1972. (Picture from: EnoAnderson)
The visionary behind this groundbreaking creation was Hisao Koike, an engineer at Yamaha, who played a pivotal role in the development of the Yamaha RZ201. Collaborating with Gerber & Henn from NSU, the patent holder for the Rotary/Wankel engine at the time, they embarked on this ambitious project. Their goal extended beyond crafting a unique motorcycle; it also involved negotiating the terms of utilizing the Rotary engine.
The visionary behind this Yamaha RZ201 creation was Hisao Koike, an engineer of Yamaha, in collaboration with Gerber & Henn from NSU, the patent holder for the Rotary/Wankel engine at the time. (Picture from: EnoAnderson)
During this period, the engine for the Yamaha RZ201 was developed exclusively by Yanmar Diesel, a Japanese company licensed by NSU for Rotary/Wankel engine production. The motorcycle's sketches and designs, bearing the project code YZ587, received approval on August 22, 1972, and were officially unveiled to the public for the first time at the Tokyo Motor Show in the same year.
Left side view of Yamaha RZ201. (Picture from: EnoAnderson)
The presence of the Yamaha RZ201 at the exhibition was a monumental surprise, even for Yamaha's own employees. This project had been shrouded in secrecy at Yanmar Diesel, with only a select few within Yamaha being privy to its existence.

In terms of design, the Yamaha RZ201 shared many components with the Yamaha TX750 and GL750, including the fuel tank, frame, front dual-disc brake system, suspension, and various other elements. What set the RZ201 apart was its utilization of a Rotary engine with two rotors, giving it a distinct appearance compared to other Yamaha motorcycles available at that time.
The Yamaha RZ201 still deserves special recognition as one of Yamaha's hidden treasures. (Picture from: EnoAnderson)
Featuring rotors with a radius of 83 mm and 56 mm, this machine boasted an engine displacement of approximately 660 cc. It was equipped with two cooling systems, namely CCR (Charge Cooled Rotor) and OCR (Oil-Cooled Rotor). Yamaha claimed that the RZ201 could deliver a maximum power output of 68 hp and a peak torque of 76.5 Nm. These impressive figures allowed the motorcycle to outperform the 4-stroke motorcycles of the era, which typically featured 750 cc engines.

The Yamaha RZ201 served as a testament to Yamaha's determination to penetrate the motorcycle market, which was then dominated by European brands and other Japanese competitors. Notably, it was the first Japanese motorcycle to employ a Rotary engine. Armed with a dual-rotor Wankel engine, the Yamaha RZ201 possessed undeniable power, positioning it as a formidable competitor to the 4-stroke motorcycles of its time.
Rotary/Wankel engine used by Yamaha RZ201. (Picture from: EnoAnderson)
Unfortunately, for reasons unknown, the Yamaha RZ201 never entered mass production. As a result, it remains a shining example of a brilliant motorcycle concept that never reached the masses. Its legacy was somewhat overshadowed by the successful mass production of the Suzuki RE5 by Suzuki in 1974. Nevertheless, the Yamaha RZ201 still deserves special recognition as one of Yamaha's hidden treasures, a testament to their innovative spirit and commitment to pushing the boundaries of motorcycle engineering.

Kept spur your adrenaline on the power of two-wheeled monster and stay alive with the true safety riding. May God will forgive Your sins and so does the cops...... *** [EKA [13032016] | FROM VARIOUS SOURCES | TOTAL MOTORCYCLE ]
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