factory) and he had worked as an
engineer on the V 1 cruise missile. The
government “suggested” that Daniel
Zimmerman share his disk valve design
and Kaaden applied it along with the
scavenging system developed in 1926 by
Adolf Schnürle to the crankcase
scavenged engine. He experimented with
the tuned exhaust system developed in
1951 by Erich Wolf at DKW.
Kaaden understood the wave nature
of two strokes, and he used oscilloscopes
to study the wave action in the exhaust.
In 1954 he had simple crankcase pump
induction engines producing 100
horsepower per liter. By 1961 his
engines were producing twice that
power. In that same year, Ernst Degner,
the champion factory rider defected to
the West and took the MZ engine
designs to Suzuki. He won the 50 cc
world championship the next year and
the Japanese two strokes dominated
motorcycle racing for the rest of the
decade. Before multi cylinder 50 cc
engines were banned in 1969, Suzuki
developed a three cylinder, 50 cc engine
that produced nearly 20 hp.
PROPWASH
14
November 2012
High Power Two Stroke Design Part 1
By Lohring Miller
NAMBA Safety Chairman
Two stroke engines have fascinated
engineers since they were invented by Dugald
Clerk in 1881. The promise of one power stroke
per revolution was counter acted by the need to
charge the cylinder with an outside system.
Many elaborate schemes have been devised to
solve this problem. DKW motorcycle engines
illustrate successful, but complex, approaches to
the problem. Even today complex new two
strokes are being introduced.
There is another way. In 1889 Joseph Day
invented a valveless, two stroke engine that used
the crankcase as the scavenging pump. This engine
was largely overlooked for high power and was
used where low cost, light weight, and simplicity
were critical. Outboard engines, chain saws, and
inexpensive motorcycles were some of the main
applications. However, in the ruins of East
Germany after World War II, this simple engine
was reborn.
The East German government was interested in
proving the superiority of their sportsmen and, in
1953, promoted Walter Kaaden to head of the
racing department of MZ (Motorradwerk
Zschopau) motorcycles in East Germany. Kaaden was forced to build simple engines
because his factory had been looted and only had very limited resources. However, he
had the rich, German two stroke history (his father was a chauffeur at the DKW
Dugald Clerk’s engine
The DKW engines
Eco Motors opposed piston engine
Walter Kaaden in 1953
The Suzuki 50 cc engine
The piston of the three cylinder motor