Hercules W-2000: The First Rotary-Powered Motorcycle

Oddly, it wasn’t until he became an emergency medical technician that he even thought to swing a leg over a motorcycle. “As a paramedic, I couldn’t understand why anyone would want to ride a bike,” Ron explains. “It just didn’t make any sense. If a dog ran out in front of you, you’d go down. In 1980, I bought a bike of my own to find out what the attraction was.”

Hook, line and sinker, Ron bit hard, and quickly grasped the attraction of two-wheeled power. He kept his first bike, a 1974 Yamaha TX500, just a few short months before buying a friend’s Honda CX500 because it had saddlebags. Ron did some touring, and the CX kept him occupied until he discovered the Gold Wing. He joined a local Gold Wing group, and soon some of his fellow riders were choosing second motorcycles.

Many were gravitating toward Harley-Davidson Fat Boys, but Ron thought those were common bikes — why not look for something unusual? This was around the time Ron and some motorcycling friends traveled to Europe, in September 2001, just after the airports reopened following 9/11. They rented motorcycles, and rode from Switzerland to Italy to attend the Milan Motorcycle Show.

Running into the rotary: the Hercules W-2000

During that trip Ron also visited the Deutsches Museum in Munich, where he saw a Hercules W-2000 rotary-powered motorcycle. It was love at first sight. “The Hercules was so different from anything I’d ever seen before,” Ron says. “If I was going to get a second bike, I wanted something different.”

Back home, Ron tried to find information about the Hercules rotary, hoping to find one for sale. He came up empty-handed. Instead, he bought a 1981 Honda CBX, but he didn’t stop there and added a Honda CX500 Turbo to his stable. On a CX500 Internet forum, a post about a Suzuki RE-5 piqued his interest — he hadn’t realized the Japanese maker had made a rotary-powered motorcycle. His fascination with rotary power still intact, Ron began researching the RE-5, and eventually bought a 1975 model simply because of its unusual engine.

That’s when he met Jess Stockwell, a rotary enthusiast and protégé of the late Sam Costanzo, who was considered THE authority on rotary motorcycles. A former Sachs employee, Sam sold and serviced Hercules W-2000s when they were new through Rotary Recycle U.S.A. in Ohio, staying in business for 40 years before selling the shop to Jess in 2009. In August 2008, Ron visited Jess in Tullahoma, Tenn., with his RE-5, and the pair tuned Ron’s Suzuki. While visiting Jess, Ron was allowed to ride a 1976 Hercules W-2000 that once belonged to Sam.

Not just any Hercules, Sam’s Hercules W-2000 was specially prepared and purportedly had been displayed at Sachs’ North America headquarters. In a deal with a Sachs executive, Sam purchased the W-2000 for his personal collection, keeping it many years before selling it to Jess. When Jess was raising capital to buy Rotary Recycle, he sold Sam’s W-2000 to Ron.

A rare Hercules

The Hercules W-2000 is referred to as the first mass-produced Wankel rotary-powered motorcycle. Envisaged in 1919 by German engineer Felix Wankel, the rotary power plant was thought by many to be an ideal engine. The Wankel rotary had far fewer moving parts than a four-stroke engine, and was theoretically more efficient.

But it wasn’t until 1957 that Wankel, working with NSU, built his first running prototype rotary engine. The transportation industry took notice of this new engine; from aircraft manufacturers to automakers to motorcycle builders, everyone seemed interested in the new technology. One of the first to license the Wankel technology was Germany’s Fichtel & Sachs, at that time Europe’s largest producer of two-stroke engines.

In the 1950s, German motorcycle maker Hercules used Sachs lightweight two-stroke engines to power their many different motorcycles, mopeds and scooters. Sachs purchased Hercules in 1963, and eventually merged with the Zweirad Union, which included the DKW brand.

Hercules developed the W-2000 using the Sachs rotary engine in the late 1960s, and a prototype machine was first shown at the 1970 West Cologne Fall Motorcycle Show. Reaction was mixed: “Should it be hailed as a great breakthrough, or a temporary mechanical diversion?” mused Dan Hunt in his opening paragraph about the prototype Hercules rotary in the January 1971 issue of Cycle World.

According to the article, 20,000 of the 294cc Sachs rotary engines found in the prototype W-2000 had already been used in U.S.-produced snowmobiles, and another version of the engine was used for powering small aircraft. In the prototype, Hercules borrowed a 4-speed gearbox and shaft drive from a BMW R27 single.

How the rotary-powered motorcycle works

When Hercules officially launched the W-2000 in 1974 (sold as a DKW in the U.K. because a bicycle manufacturer already had rights to the Hercules name), the BMW gearbox had been replaced with a 6-speed unit with chain final drive sourced from a Penton 400 dirt bike. A set of bevel gears transferred power from the rotary shaft through 90-degrees to the transmission mainshaft, and the clutch was a seven-disc affair running in an oil bath.

Of course, what is of primary interest is the Sachs rotary engine, which used a single spark plug firing a single rotor with apex seals.

As explained in the May/June 2011 issue of Motorcycle Classics in an article about Suzuki’s RE-5 rotary-powered motorcycle (effectively identical in principle): “The rotor’s tips seal against the housing to form combustion chambers. Instead of a crankshaft, a rotary uses an eccentric shaft with the rotor riding on the eccentric. A stationary gear on the end of the eccentric shaft keys the rotor to the eccentric shaft. Combustion pressure pushes the rotor away from the combustion face, causing the eccentric shaft to rotate. The shaft’s eccentric defines the throw of the rotor while the stationary gear defines the rotor’s position on its axis. As the rotor spins, its axis shifts, causing the rotor to orbit and alter the combustion chamber for intake, compression, ignition and exhaust phases.”

When first introduced, the Sachs engine was rated at 23 horsepower, a figure that was later improved to 32 horsepower. While listed at 294cc, for comparison to a piston engine that figure, in theory, should be multiplied by two for a 588cc capacity: A single-rotor Wankel produces one power stroke every crank revolution, whereas a single-cylinder 4-stroke requires two crankshaft rotations for each power stroke.

Fuel and air are mixed in a 32mm Bing carburetor, and a single exhaust header splits into two under the engine and feeds two mufflers, one on each side.

Unlike the Suzuki RE-5, which uses liquid-cooling to help dispel the great heat generated by a rotary, the Hercules W-2000 relies solely on a large axial fan at the front of the engine — and, of course, the cooling breeze of the slipstream once underway.

The running gear consists of a tubular steel frame with twin front downtubes that bend back and run over the top of the engine. As a result, the Sachs rotary appears to hang from the frame, although it’s also supported at the rear.

The front forks are Cerianis with 4.5 inches of travel, and the rear swingarm is damped by adjustable preload Ceriani shocks.

The Hercules wears 18-inch wheels at both the front and rear, and the front brake is an 11.8-inch disc, while the rear is a 7-inch drum.

Period tests of the Hercules give the machine credit for its cornering stability, but fault the 6.5-inch ground clearance as a major detractor in its cornering ability.

“If it weren’t for the limited ground clearance,” Cycle World said in its March 1976 review, “handling on the Hercules would far exceed the capabilities of the engine.”

Cycle World said the W-2000 would burble along at an indicated 60mph, and would climb a hill in sixth gear at 50 to 55mph, but said it took at least one and most probably two downshifts to overtake a car on the highway: “…performance is not spectacular, just adequate if the driver of the car you’re passing doesn’t stand on it at the same time. If he does, you lose,” Cycle World said.

Original distribution of the Hercules W-2000

Ron says that while the W-2000 might well have been the first rotary-powered motorcycle offered publicly through a dealer network, he thinks it was built solely to test consumer acceptance of a rotary-powered two-wheeler. His research indicates the first container of 40 Hercules W-2000s — 34 with red tanks and 6 with yellow — arrived in the U.S. in January 1975 and was delivered to Rotary Recycle U.S.A. The Rotary sales team visited dealers across the U.S., espousing the virtues of the Wankel. New dealers were enlisted, and rising orders for the $1,900 rotary showed there was some interest.

In May 1975, Hercules introduced the KC-30 GS Enduro rotary-powered dirt bike, and shipped two to Rotary Recycle. Although it generated great excitement, the KC-30’s $2,900 price tag killed any sales of the model. And by the end of summer, sales of the Hercules W-2000 had slowed to a trickle, perhaps because Hercules had announced an oil-injected model was coming for 1976. Early machines required pre-mixing the oil and gasoline.

The W-2000 Ron owns is one of 199 “automix” oil-injected 1976 machines produced. Of those 199, it is unknown how many landed in the U.S. Unlike the Suzuki RE-5, there is no crankcase oil used in the W-2000 engine, and it does not run two-stroke oil. Instead, Ron runs Castrol 20/50 in the injector tank. Ron’s W-2000 is finished in Midnight Black, although Danube Blue was an option for 1976. Presumably because it was displayed at Sachs’ head office, Ron’s Hercules features a factory-polished fan cover and transmission.

After purchasing the W-2000 from Jess — with less than 6,000 miles on the clock — Ron changed the front brake fluid and added a rare factory accessory right-hand mirror. That’s all he’s done since buying it. The tires had been changed while in Jess’ care, and Ron has carefully added just more than 300 miles to the Hercules.

Because he owns a Suzuki RE-5 and the Hercules W-2000, Ron can speak with some authority about these mid-1970s rotary-powered motorcycles. “The Japanese went one way, and the Germans went the other,” he says. “The RE-5 has five different cavities for four different fluids, the oil pump and the points are all running off of something else, and the carburetor is a bit complicated. The Hercules, by comparison, is very simple, with a fan in the front, and the ignition runs off the same shaft.”

Ron says that running, the Hercules sounds like a cross between a two-stroke and a four-stroke. On the road, low-end torque is a bit lacking, but with the 6-speed gearbox he can keep the W-2000 moving along on the highway. For him, the ride is part of the charm, and he will continue to put miles on the Hercules W-2000, if perhaps a bit slowly.

Just 1,784 of the rotary Hercules motorcycles were built, and Ron says the plug was pulled not because they weren’t well made, but because they missed their set monthly sales quota by 25 units. “It was just too weird, I guess,” Ron says of the W-2000. “But that’s what attracts me to these orphan bikes — they might be weird, but they’re also different.” Which bring things full circle, really, because that’s the same way Ron first approached motorcycling — differently. MC

Hercules W-2000 press reports

“Surprisingly attractive in a Teutonic way, it is solidly built. The seating is comfortable and the handling is slow and graceful. It is hardly a sporting machine, nor does it have sporting performance, But it is flexible, smooth, comfortable and would undoubtedly prove a pleasure on extended journeys.” – Cycle World, January 1971

“It’s not one of those bikes that offer spirited performance. Speed is simply built up mile per hour by mile per hour. If you are over 4,000rpm, there really isn’t much advantage to shifting. And cornering is effectively limited by conservative ground clearance. So, the Wankel 2000 is not a bike for sport. It’s a bike for daily commuting.” – Cycle World, March 1976

“Sixth gear at 65mph is perfect. But if you try to ease down to legal speed, the tach drops from 4,000 to about 3,200 and the engine gets rough. Gearing down doesn’t help, but adding power does. You get the impression that the Hercules doesn’t agree with our politicians about how fast we should travel.” – Cycle, June 1976

Resources

• Hercules website
• Hercules Wankel 2000