Remarkable design, as seen in a YouTube video from the engine rebuild. It's a twin, with two separate castings for cylinders, heads and valve covers, which are sitting side by side as though they were each cast as one part. The crankcase is split vertically, with completely separate bores to receive the cylinders, and a full gasket between the two halves (unlike a Triumph 650). It must have been done this way to help retain good oil sealing?
It looks like a big bench seat was originally fitted.
Moto