I need help

Pictures are two views of an engine that I got a couple years
ago. I can’t find a name for it. It has four bolts to hold the
igniter plate on. The odd thing of it is the carburetor goes in
front of the head just above the exhaust valve. The intake goes in
through the igniter hole with the spring in going straight out
right side of engine. Gas Tank and Base The water hopper is cast by
itself. The cylinder and base with main bearing mounts altogether.
The water jacket just slides on over the cylinder with jacket on
the back then head goes on to hold water jacket in place. Please
help!