The Hercules Engine News

By Staff

20601 Old State Road Haubstadt, Indiana 47639

By early 1925 the horsepower of Hercules and Economy engines had
been increased simply by upping the rpm about ten percent. At this
same time the Hercules color was changed from dark green to a
lighter green color. These changes are likely well known among
Hercules engine enthusiasts.

Not so well known was the introduction of 1 and 2 HP model SK
throttling governed Hercules engines at that same time. The
Hercules block was slightly modified with additional holes in the
base for the throttle rod to go from the governor to the inside
above the fuel tank and out the front to the fuel mixer.

A water-cooled head is used and where the normal mixer screwed
in, it was modified to provide a flat place for the two fuel mixers
to bolt on. This mixer with its starting gas reservoir is quite
similar to the mixer on the later and more common XK and JK
kerosene engines. Since the water-cooled head is thicker on the 1
HP than the hit and miss engine head, a longer side rod is

Shown at right is a page from the manual with the special
instructions for these engines.

How many of these 1 and 2 HP SK Hercules engines were built and
currently exist? It is likely that fewer than 1,000 of the 1 HP
size were built. Probably only a few hundred of the 2 HP size were
built. Here is a listing of those currently known.

21/2 HP



1 HP


late 1925


early 1926


late 1926


late 1926





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