Looks a bit like an early Neracar
How does it steer?
It does look a bit like one in some ways Sav, but not sure it is. Could be some Ner-a-Car parts in it though I guess.
Google brings up loads of them, of different years and in seemingly innumerable variants - but the saddle on all Ner-a-Cars I've just been eye-balling was well forward of the rear wheel not directly over it and the fuel tanks were under the saddle, in most cases a round one, although there were quite 'posh' versions with a shape rather like in musky's pic - but under the seat and oriented about 90° differently. Also, not sure whether any of them had belt drive , or ever had the final drive on that side. . Chain - on the other side of the wheel - seems to be what they used from what I can see.
The transfer on the tank is hard to figure. Ditto the engine, but all sorts of engines, 2 strokes and four, got used in these sorts of velocipedes.
So I dunno, - but I bet someone here who's well into early machines will.
Centre hub steering? Like wot Bsareg just said . . .