BY CLARENCE LEE PHOTOS BY CLARENCE LEE
IT HAS BEEN 32 YEARS now since O.S.
introduced their first 4-stroke engine: the
FS- 60. I will always remember during a conversation with Don Dewey, who was the
editor of the now defunct R/C Modeler Magazine, how we wondered what need there
was for a 4-stroke model engine. Boy, were
we wrong! The interest in 4-strokes took off
like a rocket and today the 4-strokes outnumber the 2-strokes at many flying sites.
Actually, 4-stroke model engines have been
in existence since the late 1930s. These
would include the 1938 Feeney, first introduced as the .687ci Model C; followed by
the .91ci Model B and 1.176ci Model A; the
Leja, marked in 1947 with only 10 having
been made; the English Channel Island
Special marketed in 1949 and the Gannet
marine engine marketed in 1958. Then, we
also have the Morton M- 5, 5-cylinder
radial, marketed in 1947. However, these
were all spark ignition engines requiring a
set of contact points, coil, condenser, and
Although many people believe the O.S.
FS- 60 was the first glow ignition 4-stroke to
be marketed, this is not the case. An engine
called the Kalt FC-1 preceded the FS- 60 by
several months. The Kalt FC-1 was designed
and produced in Japan by a gentleman
named Hiroyuki Oki, a well-known Japanese hobby industry leader who founded the
well-known Kalt helicopters in 1974.
The Kalt FC-1 was “over square” in
design and had a displacement of .45ci. Features included open rocker arms and a true
hemispherical combustion chamber with
domed, single, ring and piston. As can be
seen in our photograph, the Kalt FC-1 was
a very attractive engine. The engine in the
photograph is from the collection of Randy
Linsalato, who in conjunction with his wife
Anching, owns K&B/MECOA. I do not have
a Kalt in my engine collection, so if any of
Above: This is one of the first 4-
stroke engines to be used in the
modeling world. It is a 1938
Feeney and actually uses a spark
plug for ignition purposes.
Above: The first glow-ignition 4-stroke was the Kalt FC-1 designed by Hiroyuki Oki. Its displacement was
.45ci. This view clearly shows the Kalt’s exposed rocker arms, the short exhaust stack and the forward
angle of the glow plug.
our readers have or know of one for sale at
a reasonable price, please let me know. Let’s
answer some letters.
U I am having trouble with the idle on my
Enya R120. I have the air bleed screw almost
all the way out and it still loads up at idle and
really stumbles when I open the throttle. I took
the carb apart and the air bleed hole was clear.
I am running the engine inverted with a glow
driver. Omega 10% fuel, 15x6 prop and a Fox
miracle plug. Any suggestions?
FRANK HANSON, DEARBORN, MI
Frank, as I have said many times over the
years in the Engine Clinic column, any time
you run an engine inverted you can expect
idle and acceleration problems. However,
the 4-strokes are usually a little more toler-
ant in this regard due to the glow plug being
offset so that it does not become a sump
where raw fuel can collect. Even so, things
become more critical with an inverted
installation when it comes to mixture
adjustment, tank position, etc. You did not
say how much running time the engine
has. The first things an over-the-hill engine
will exhibit are idle and acceleration problems due to lower combustion heat.
However, if the air bleed adjustment hole
has to run out of range, you probably have
your fuel tank mounted too high. The centerline should be no higher than the
centerline of the needle valve and preferably 1⁄ 4 to 3⁄ 8 inch lower. Lowering the fuel
tank should help considerably. Although
the Fox Miracle plug usually works very
well, you might also try the O.S. “F” plug.
You might try enlarging the air-bleed hole a