DkW ULd 250 1939
After his success with the DkW URe, designer
Zoller further improved his two-stroke, double-cylinder engine in 1938.
The chassis part of the motorcycle remained almost the same when DkW put the new
model—the ULd 250— into the field. The engine, however, was considerably
changed. In the URe the cylinder pump was horizontal at a 90° angle to the two
engine cylinders. In the ULd the cylinder pump was mounted vertically at the
front end of the engine. At the supercharger head of the new model there was a
rotating valve served by two carburetors.
Serviced by ,the same large staff of men and equipment as the URe, the ULd won
the 1938 Isle of Man Tourist Trophy at record speed. Because of its excellent
acceleration and high speed, the rider Ewald Kluge was able to stop twice for
fuel, while his adversaries could stop only once.
This compensated for the ULd's high-er-than-average
fuel consumption. Kluge still managed to cross the finish line twelve minutes
ahead of the second-place motorcycle.
Although the DkW ULd 250 used more fuel than any other comparable or larger
motorcycle and tended to be unstable both in curves and on the straightaway,
Kluge managed to ride it to the European championship in two consecutive years,
1938 and 1939.
A watercooled 250 c.c. two-stroke with three
pistons, a rotary valve and only one sparking plug. That is part of the
specification of the D.K.W. on which Ewald Kluge won the 1938 Lightweight T.T.
by over ten minutes! In doing so he cracked round to raise the lap record almost
3 m.p.h. by clipping 57 sec. from it.
Basically his machine was virtually a
split-single (like the Puch machines of post-war years) with watercooling and
two rearward facing exhaust ports. A third piston, of considerably bigger
diameter than the "working" pair, was fitted in a pumping cylinder that lay
horizontally in line with the machine, forward of the crankcase. Above this, and
forward of the watercooled block, was mounted a transverse rotary valve that had
an Amal carburetter at each end\ Mixture was taken from both carburetters
through the rotary valve to the big cylinder which was only a pump. This rammed
the mixture into the working chamber—and out through the exhaust ports at slow
The model quickly achieved fame for its fantastic
noise, its fantastic speed and its fantastic petrol consumption. To cope with
this last, unwanted, attribute it had a massive tank that enshrouded the header
tank of the radiator.
Although first glimpse at the photograph suggests that it had plunger rear
suspension, this is not so; the machine has a rear pivoting-fork with a pivot
bearing on the seat pillar tube and the "plunger" units merely contain the
Despite a full duplex cradle frame, and the rear
suspension, the model had not got a very good reputation for handling—but its
speed still made it a winner.
Engine: watercooled split-single 250 c.c. two-stroke, with rotary inlet valve
and supercharging pump cylinder.
Ignition: flywheel magneto.
Transmission: chain via four-speed gearbox.
Frame: duplex cradle with swinging-fork rear suspension controlled by
"plunger-type" spring boxes.
Forks: single-spr'ng girder with friction damping.