Robban!
I very much appreciate the photo for my carbstamp collection!
Unfortunately, I can only add to my list of "mystery carbs."
The lack of a vent on the sides indicates that it must have a vented venturi, like an M-88 and Indian models.
The highspeed needle knob has an unusually small hole in its center.
Since venturi-vented H-D models were usually military, with fixed jets and capped HS needles, I would suspect the fixed jet has been plugged, and the needle is a replacement, perhaps of modern manufacture.
The lowspeed spring collar appears to be a thick one (?), suggesting it is a 1941 production (or replaced with a later OHV collar at some time.)
L&L literature cites rotating the valve of the bowl close to the choke mechanism; Positioned at ninety degrees to the carb body, as yours is installed, usually causes the float to hang up upon the bowlstem.
I would be greatfull if you could post us the venturi bore measurement,
and any other intermal observations when you get inside of it.
Thanks in advance,
....Cotten
