In 1919, young German engineer Felix Wankel started thinking about an engine that could be an alternative to the classic internal combustion engines. The engine would still work via internal combustion but instead of pistons and rods, Wankel thought about a simple rotor that would activate a shaft. Wankel got his first patent in 1929, and 28 years later (1957) the very first rotary engine prototype was born thanks to its partnership with German car and motorcycle manufacturer NSU. Considered much simpler and smoother than a four-stroke engine, rotary technology was licensed by NSU to other brands like Mazda for cars and German motorcycle manufacturer, Hercules. In the beginning of the 70s, Suzuki was looking for technology that could put them at the center of the scene and leave other manufacturers behind. At the end of 1974, Suzuki released what Cycle magazine qualified as “the most elaborate motorcycle ever offered to the public”, the rotary-engined RE-5. Check out Motorcycle Classics to learn more about how the RE-5’s rotary motor works.
The RE-5 engine displaced 497cc and was therefore categorized as a 500cc machine. However, CCs on a rotary are not exactly the same as CCs on a classic engine, so we usually consider that the power created by a rotary engine has to be doubled to compare it to a classic engine. The RE-5 was consequently as powerful as a 1000cc traditional bike. Developing around 62hp, the bike had a top speed of 105 mph. The major problem the bike was facing was its weight: dry weight of the bike was approximately 510 pounds. As a comparison, the 1969 CB750 had a wet weight of 499 lbs.
As you may suppose, the RE-5 was a commercial failure. Despite being revolutionary, the engine had a lot of drawbacks compared to a traditional one. As we saw above, it was desperately heavy, which made city usage complicated. Even though the engine was “simple” inside, it required more parts to make it run. Two oiling systems, two ignition systems and two cooling systems were necessary to keep the rotary from exploding due to the heat it produces. The RE-5 lasted 2 years, and probably not more than 6,000 were ever produced. Due to the money invested in that project, Suzuki nearly had to close down.
Still, in my opinion, the RE-5 is a piece of history, and a chance to ride something really different. Despite being not so simple, the rotary engine was an interesting concept, and will likely gain value in the future. You can go back to Motorcycle Classics to learn more about the bike in general.
The RE-5 presented here is an “A” model as it is from 1976 (1975 models were M models). It appears to be in really good condition. Despite not being very detailed about the bike, the seller claims that it is running. With the odometer showing 21,200 miles, the bike seems to be in fairly original condition.
Find this RE-5 in Madison, Wisconsin here on Cycle Trader for $6,000.