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Around 1949, Zundapp began preliminary design work on an entirely new model for the KS
series. This motorcycle was updated with plunger rear suspension - a major improvement
over none - and telescopic forks to replace the traditional Zundapp parallel four link
fork found on its predecessors.
Early efforts involved a small displacement engine but Zundapp engineers began playing
around with installing the wartime KS600 motor in the frame. Ernst Schmidt, chief designer,
liked the idea. In late 1949 the first prototype emerged, painted black, with a beefed up
chassis to handle the larger motor.
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The Zundapp KS601 Arrives on the Scene
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In early 1950 a second prototype was completed. With an engine that differed from the
original KS600 in many respects, the new bike was rechristened the KS601. To further distinguish
it, not only from BMW but also prior Zundapps, the black frame now sported fenders, tool
box, fuel tank, fork cover, and head light housing all appointed in the famous Zundapp
lime green.
The newly designed 597 cc motor, with two
Bing
carburetors, produced 28 Hp at 4700 Rpm with peak torque of 33.6 Ft. Lbs
at 4000 Rpm. This was notable power - more than the Volkswagens of the time - and made the
Zundapp KS601 an immediate hit with enthusiasts. The motorcycle's unique appearance and its
new engine earned it the well known title of "Green Elephant".
As with the production bikes,
the telescopic forks
of the new chassis had almost 5" of travel but furnished no dampening. A
shock absorber
mounted on the triple clamps between the fork tubes and bearing on the heavy front fender
directly above a strong brace provided compression dampening. In the rear, the
plunger type
suspension had about 2.5" of undampened travel and was carried into production unchanged,
the only exception being the axle trailing the shock housings rather than leading as on the
prototype.
Power was transmitted from the engine via a two disc dry clutch in a heavy flywheel driving
the peculiar but extremely smooth shifting and reliable duplex chain drive transmission,
shown in the sectional view on the previous page. From the transmission a drive shaft with
two kardan U-joints delivered power to the
spiral bevel ring and pinion
final drive which drove the rear wheel via a splined axle that engaged the hub. I have seen
final drives with both straight and tapered splines, both clearly designed for use in the
KS601 because there were provisions
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Sectional View of Zundapp KS601 Engine and Components.
Click image for
larger view of the Zundapp KS601 engine.
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1
2
3
4
5
6
7
8
9
10
11
12
13
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Right-hand Cylinder Head
Sparkplug with Cap
Pushrod
Right-hand Cylinder
Mushroom Tappet
Tappet Guide
Camshaft
Ignition Coil
Camshaft Gear
Breather
Voltage regulator with
Reserve Current Cutout
Valve Adjusting Screw
Rocker Arm
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14
15
16
17
18
19
20
21
22
23
24
25
26
27
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Valve Spring
Valve
Compression Rings
Piston Pin
Piston
Connecting Rod
Oil Sump
Oil Filter
Crankshaft
Crankshaft Gear
Oil Pump
Armature
Generator
Contact Breaker
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for the plunger suspension in the castings. I asked James Marshall, aka the Zundapp Fool, why
the two versions. He explained the tapered or "cone" version was used on the 1951 and '52 models.
In 1953, the factory began producing the straight or "barrel" spline, presumably because it was
cheaper to manufacture. Interestingly, both the front and rear Zundapp KS601 wheels have the
final drive spline in the hub so they can be used interchangeably, which allows tire rotation to evenly distribute wear, but one needs to remember the two types of spline if purchasing another
wheel.
The first production KS601 left the factory in the summer of 1951 after extensive and successful
testing of the prototype versions. This newest Zundapp received enthusiastic reviews from the
various motoring magazines of the time. It proved to be popular not only with the motor sports
crowd, but also with average owners who quickly came to appreciate its rugged dependability.
In 1954, a father and son team rode a Zundapp KS601 on a highly publicized 20,000 mile trip around
the world, after which the bike was dismantled by a group of motorcycle journalists and factory
technicians. They reported the machine showed surprisingly little wear after the incredibly abusive
journey, and were awed by its durability in conditions they felt would have destroyed many of the
bikes offered by Zundapp's competitors.
Despite such positive attention from the press, sales of the Zundapp KS601 were lagging
considerably behind similar models from BMW. The factory adopted a number of strategies in the
attempt to boost interest, including introduction of the KS601 Sport with 34 horse instead of
the standard 28. They offered a number of additional color choices and targeted the United States
in a campaign to get a toe hold in that growing market. All to no avail. Part of the issue was
Zundapps being widely viewed as heavy duty sidecar machines. Despite handling that was
superior even to BMW's they just couldn't shake that reputation with the solo riders. Also, the
world economy was picking up and more people could afford to purchase cars, which had obvious
and attractive advantages over motorcycles for practical day to day transportation.
In a final attempt to bolster sales the Zundapp KS601 Elastic was introduced in 1957, featuring
the Sport engine and a new swing arm rear suspension. Aimed exclusively at the US market, this
fine motorcycle was too little too late. Production of the KS601 in all its flavors from 1955 to
1958 failed to reach 1000 motorcycles. Total production across all the years of its manufacturer just
barely topped 5000. In 1958, Zundapp sold the Nuremberg factory to Bosch and production of the
Zundapp KS601 ceased.
Even those few Green Elephants were able to impress an admiring public with their remarkable
ruggedness and reliability. Devoted Zundapp KS601 owners formed organizations all over Europe.
One such group began an annual winter ride in 1956, the
Elefantentreffen, which grew at one point to tens of thousands of participants. The meet
survives to this day - despite having experienced some tribulations - and still boasts a couple
thousand attendees, but necessarily few on KS601's.
As the years passed parts became more difficult to obtain inspiring numerous approaches to keep
the venerable KS601 going. These included clubs organized to purchase large lots of spares and forays
into modification of parts from other vehicles to be used in the Zundapp. Now, thanks to the
KS601's well earned and enduring popularity, aftermarket parts sources are cropping up all over
Europe. Unfortunately, those few outlets which once existed in North America have pretty much
vanished.
In 1984, the Zundapp marque and all the equipment was sold to a firm from Tianjin China which
primarily built smaller displacement bikes for a country that views motorcycles as basic
transportation. They also produced the WWII era KS500 which was apparently of quite high quality and
true to the original, opening a new parts supply for the gleeful owners of those models but not, alas,
the KS601.
In 1999, a German firm purchased the Zundapp name. The new owners are known to have substantial
knowledge and interest regarding the KS750 but it is not yet clear what their intentions might be.
While I've been unable to find any reference to current activity, it's encouraging that the marque
is once again German owned. Who knows? Maybe we'll be able to buy our spare parts from Zundapp
itself once again.
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