Home Motorcycle A Suzuki RE5 Wankel rotary motorcycle

A Suzuki RE5 Wankel rotary motorcycle

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The Suzuki RE5 was a Wankel rotary engine motorcycle developed in the early 1970s. It was intended to be a showcase for the future of Suzuki’s motorcycle division, but it quickly proved to be a costly and public failure, costing Suzuki the company worth millions of dollars and resulting in many thousands of unsold motorcycles.

In recent years, surviving examples of the Suzuki RE5 have become increasingly sought after by enthusiasts and collectors who appreciate the engineering that went into the design, not to mention the Giorgetto Giugiaro styling and good handling according to the specifications. standards of his time.

Quick Facts – The Suzuki RE5 Rotary Motorcycle

  • When Suzuki licensed Wankel rotary engine technology from NSU in the early 1970s, they embarked on a potential new direction for the company.
  • World renowned designer Giorgetto Giugiaro was hired to design the bike, Suzuki engineers developed and patented a host of new engine technologies, Suzuki created an all new production line for their rotary engine designs.
  • The first, and eventually last, Suzuki rotary motorcycle was the RE5 first unveiled to the world at the Tokyo Motor Show in late 1973. It would only be sold for two years, 1974 and 1975, before being discontinued due to bad sales.
  • The Suzuki RE5 was powered by a single-rotor Wankel rotary engine with water and oil cooling, with a displacement of 497 cc producing 62 hp at 6,500 rpm and 54.9 lb-ft of torque at 3,500 rpm. min.

The Wankel rotary engine

For the uninitiated, the Wankel rotary engine was developed by German engineer Felix Wankel, he first patented the design in 1929. in the 1950s, after World War II, he began working for NSU (NSU Motorenwerke AG) and in 1957 he had a working prototype.

Video above: This 3:25 film by Matt Rittman shows how a Wankel engine works. It starts with the engine assembly and names all the major parts, then shows how they all work together.

Unlike the more common Otto Cycle engine which uses pistons, connecting rods, valves, and cams, the Wankel rotary engine uses a triangular rotor that spins in a chamber.

On paper at least, it appears to be a superior design due to few moving parts and the remarkable simplicity of the design, but lingering issues including poor fuel efficiency, higher emissions, and apex seals. subject to wear and tear, have limited generalizability. adoption of technology.

That said, it’s important to note that far less money was spent developing the Wankel engine than developing the standard Otto cycle engine, and with a comparable investment, it’s likely that many problems could have been resolved or significantly reduced.

The Wankel engine remains in limited production today, Mazda has a team working on it, and in the UK former Norton rotary engine engineer Brian Crighton developed the Crighton CR700W – a 220hp rotary motorcycle which is currently in production.

Description of the imageExcept for this unusual engine, the rest of the Suzuki RE5 is relatively standard for its time, including the duplex cradle frame, twin rear shocks and front disc/rear drum brake arrangement.

The Suzuki RE5: History + Specifications

In the late 1960s and early 1970s, many car and motorcycle manufacturers were looking for the next big thing. Some experimented with electric transmissions, others with gas turbine engines, many invested heavily in the development of two-stroke engines, and a few experimented with Wankel rotary engines.

On paper, the Wankel looks like the perfect engine for motorcycles. They are exceptionally simple, with no valves or cams, very few moving parts and remarkably low weight compared to a traditional four-stroke engine of the same capacity.

Suzuki executives invested heavily in Wankels, licensing technology from NSU and spending millions of dollars to develop a production-ready engine. They filed a number of new patents and built an entire production line specifically for their planned line of new Wankel motorcycles.

Suzuki engineers developed an ingenious but complicated single-rotor engine integrated into its 5-speed gearbox. It had water and oil cooling, a two-stage Mikuni carburettor, CDI ignition, wet multi-disc clutch and sintered ferrous alloy and titanium carbide apex seals.

Cutaway view of the Suzuki RE5 rotary engine

Description of the imageThis is a cutaway illustration of the RE5 engine, you can see the single rotor on the left side feeding the gearbox by means of a duplex chain, and from there to the final drive by means of a chain regular.

Power was impressive for its 4,977 cc displacement, with 62 hp at 6,500 rpm and 54.9 lb-ft of torque at 3,500 rpm. Top speed was 168 km/h (104 mph) with a standing quarter mile of 14.02 seconds at 94.24 mph (151.66 km/h).

Suzuki had developed the RE5 not as a superbike or racing bike but as a touring bike, a new frame was developed and paired with a relatively standard suspension arrangement for the time – telescopic forks up front and dual rear shock absorbers.

Period magazine reviews complimented the Suzuki RE5 on its handling, it had excellent braking ability thanks to its dual front discs and rear drum.

The end of RE5

Reviews were equally rave about the weight of the bike, tipping the scales at 573 lb (260 kg) ready to ride (with fluids). The general consensus was that the RE5 was too expensive, too heavy, and not powerful enough.

Sales were extremely low for the new model, well below Suzuki’s projections for the series and it was discontinued after just two years with thousands of bikes unsold worldwide.

Suzuki RE5 Moto 8

Description of the imageThe large radiator was a necessity due to the fact that rotary engines tend to heat up, exhaust gases can reach nearly 1000ºC (1832ºF).

Rumors persist that Suzuki sent much of the equipment and my unsold motorcycles out to sea and had them dumped off the coast of Japan – but no confirmation of this story has ever been found.

Many modern riders were drawn to the unusual RE5 after discovering that if you use the bike for its intended purpose, cross-country, it’s actually a great machine. Many have not survived after years of neglect, but those who have now demand a price premium.

The 1975 Suzuki RE5 shown here

The Suzuki RE5 you see here is a low mileage survivor from 1975, it has only 12,500 miles on the odometer and remains in excellent condition throughout.

This motorcycle was sold new in the USA before being more recently imported to the UK by its current owner, being registered for the road for the first time in England in April 2021.

It is currently part of the seller’s motorcycle collection, and it has been decided to reduce the number of bikes, so this is offered for sale in a live online auction on Car & Classic.

If you want to know more about it or register to bid, you can click here to visit the listing.

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Images courtesy of Car & Classic

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