1949 CRF450: Okay, maybe not, but this
was the first Honda two-stroke.
REVERSING THE TREND
In the July 2014 issue, Honda
designer Yasuhiro Yokomoto said
that Honda had designed a back-
wards engine just like Yamaha but
elected not to build it. How many
other companies have toyed with
turning the cylinder around?
As strange as it may sound,
Honda’s first-ever production motorcycle, the 1949 Dream D, had a
reverse cylinder design—so, as
incredibly original as the reverse
cylinder of the 2010-2015 Yamaha
YZ450Fs may seem, it is not an
original idea. The MXA wrecking
crew searched our memories, and
those of our grandfathers, to come
up with a fair-to-middlin’ history of
reverse cylinder motorcycle engines.
In 1922, the 204cc Opel Motoclub
was a water-cooled, OHV four-stroke
with the cylinder turned around
backwards. The company would
later specialize in automobiles.
Then, in 1925, the German
company Orionette produced the
246cc TS model. The Orionette was
a unique two- and four-stroke
combined design that used a backwards cylinder. The engine was the
brainchild of famous pioneering
helicopter designer Engelbert
One of the best-known reverse
cylinder bikes of all-time was the
1939 DKW SS250. This split-single
engine design had two pistons, a
yoked connecting rod, common combustion chamber and a rear facing
The first official production motorcycle by Honda was the 1949 Dream
D. This 98cc two-stroke featured a
reverse cylinder, two-speed transmission and stamped-steel frame.
Its 50mm by 50mm bore-and-stroke
engine pumped out 3 horsepower at
5000 rpm. In 1951, Honda removed
the reverse two-stroke engine and
put in a 146cc OHV four-stroke.
Equally important in the timeline
of backwards cylinders was the
1960 MZ RE125. This East German
road racer was designed by Walter
Kaaden, the father of the expansion
chamber. Kaaden’s water-cooled,
rotary-valve, reverse cylinder design
was copied by the Japanese when
MZ’s Grand Prix rider, Ernst Degner,
defected from East Germany with
a complete set of Kaaden’s secrets.
Surprisingly, he defected from
East Germany while leading the
1961 125cc World Road Racing
Championship with only one race to
go. Degner and his wife and children
escaped from East Germany in the
trunk of a car. Degner immediately signed a contract with Suzuki.
According to sources, Degner arrived
at the Suzuki factory in Hamamatsu,
Japan, under the pseudonym of
“Eugene Muller,” taking with him
some MZ parts (cylinder, piston,
crankshaft and rotary-valve) plus
some blueprints. Degner shared most
of Kaaden’s ideas with Suzuki. This
paved the way for the Japanese
domination of motorbike racing in
the following decades. The most
notable Kaaden-clone was the 1963
Suzuki RT63 road racer.
Yamaha itself is no stranger to
turning cylinders around backwards.
The 1988 TZ250U twin-cylinder road
racer had the exhaust pipes in the
rear and the twin carburetors in the
front. The cylinders were laid down
so radically, the carbs were only
inches above the ground and inches
behind the front tire.
The ill-fated, overweight, hard-start-ing, undersprung, unreliable 2001
Cannondale MX400 was the most
notorious reverse cylinder design
ever made. After investing $80 million in its failed motorsports venture,
bicycle manufacturer Cannondale
filed for bankruptcy in January 2003.
And finally, Ossa produced a
fuel-injected, reverse-engine trail bike
that has seen limited production.
Whether we will ever see the bike in
the USA depends on the outcome of
Ossa’s new merger with Gas Gas.
Slam-fest: You tighten KTM’s steering by
pressing the top triple clamp down.
POOR MAN’S STEERING
The steering on my KTM 350SXF
feels very light. I’d like to tighten the
steering head down to slow it down,
but when I took the top triple clamp
off to tighten the bearing, there was
no adjuster nut or lock nut on the
steerer stem. How do I do it?
In simplest terms, KTM slam-fits
the top triple clamp directly onto
the steering stem bearing. This is
definitely different from the conventional way of doing it, but tightening
the steering head bearing to create
the poor man’s steering damper is
incredibly easy. You don’t even have
to remove the top triple clamp to do
it. First, loosen the top triple clamp
pinch bolts (including the one that
clamps the triple clamp to the steerer tube). Second, put a wrench on
the aluminum steerer stem nut and
begin to tighten it. As you tighten it,
the top triple clamp will move downward. Third, stop after a few turns
and check how freely the handlebars
swing back and forth from left to
right. Fourth, tighten the steerer
stem nut until you feel the amount
of drag you desire at the handlebars
and then tighten all five pinch bolts.