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The Zundapp KS601

   Generally, upon seeing a Zundapp KS601 for the first time, folks ask "What kind of BMW is that?" It can be difficult to convince them that, while BMW's success with the opposed twin did not escape the attention of Zundapp's engineers, the KS601 and its ancestors evolved exclusively on Zündapp-Werke drafting tables.

A Little History - The KS601's Predecessors

Zundapp-Werke was an established company before venturing into the world of motorcycles in 1921, having produced detonators for explosives since its founding in 1917. The company's original name was Zunder-Apparatebau-GmbH. The name Zundapp was the union of the words zünden, to detonate, and apparatebau, apparatus. If I recall correctly their specialty was bomb fuses.

Owner-industrialist Fritz Neumeyer also had the vision of offering a reliable high quality motorcycle under the Zundapp name. He succeeded to the point that Zundapp was producing more than 28,000 motorcycles per year by 1929. Things didn't go so well during the world depression but Zundapp held on and emerged in 1933 with a host of new models designed by engineers Richard and Xaver Küchen, including the K models. The fledgling K series included opposed twins of 400 and 500 cc nominal displacement, and opposed four cylinder motors of 600 and 800 cc's, all flat heads. The 1933 K500 produced 12.5 HP while the K600 and K800 boasted 16 and 20 HP respectively, both at 4300 Rpm.

The products of Zundapp-Werke's Nürnberg-Schweinau plant, these bikes embodied many of the features that would define the KS601 including shaft drive via a novel duplex chain drive transmission, although these early versions were stick shifts. They were considered by many to be technically superior to their contemporaries and soon earned a reputation for endurance and reliability.

In 1935, the year the firm's founder died, Zundapp introduced the KS500 model, or Kardan Sport 500. Kardan referred to the U-joints on the shaft drive and sport referred to the new overhead valve motor which produced 24 HP at 5200 Rpm. Like the KS601, these motors had cast iron cylinders, aluminum heads and valve covers, with a carburetor on each cylinder drawing air through a single filter beneath the upper engine cover. Also, these were the first Zundapps available with a foot shifter.

In 1938 the KS600 was brought into production. The cylinders shared a single carb but the motor developed 28 HP despite that. 18,000 KS600's were built between 1938 and 1940 with most going to the armed forces. These bikes retained the girder front suspension, apparently with friction dampers although air/oil shocks were played with at some earlier point.

With war imminent the Zundapp factory jumped headlong into design of the super heavy KS750 which entered production in 1941. Intended strictly as a sidecar machine the KS750's conventionally geared transmission, as opposed to the hallmark Zundapp duplex chain tranny, was shifted via two hand levers on the side of the gas tank. Another controlled a differential which in normal operation delivered 60% of the torque to the bike's rear wheel and 40% to the sidecar wheel and could be locked when negotiating difficult terrain.

Click for larger view of Zündapp KS601 Engine and Transmission
Sectional View of Zundapp KS601 Engine and Duplex Chain
Drive Transmission. Click image for larger view.

Starter Bevel Gears
Clutch Lever Bar
Air Filter
Duplex Chain Drive
Multiple Disc Clutch
Universal Joint Shaft
Clutch Thrust Bearing
Main Shaft
Reduction Shaft
Oil Drain Plug for Engine
Oil Filler Screw for Gear Unit
Shifting Fork
Gearshifting Mechanism

To fully dispel the myth that Zundapp is a derivative of BMW, much less an inferior copy, the heavy sidecar KS750's were so superior to BMW's offering that the German government compelled BMW to incorporate many of the Zundapp's technically advanced features into their own military motorcycles. Probably not very popular with BMW, but who was going to argue with der führer? The dude had breath that made his temper look like Pollyanna's, not to mention a flatulence issue of, perhaps literally, historical proportions!

From 1942 the KS750 was the only motorcycle Zundapp built with total production exceeding 18,000 units. During the war the factory also built aircraft parts, bomb fuses, and other ordinance. It was basically bombed out of existence toward the end of WWII. After reconstruction of the buildings production focused first on grain milling equipment, then sewing machines. Motorcycle production did not resume until 1947, mostly dedicated to smaller displacement sidecar machines to fill the need for inexpensive transportation in post war Germany.

Next - The Zundapp KS601 Arrives on the Scene

Acknowledgements & References

Last updated 01-16-18
Email:  mechanique at wmol dot com

Zündapp KS601 drive shaft, U-joints, and pinions.