That looks very much like the generic version of the Harley "Shortster" a 65cc mini made by someone and sold by Harley in the early 70's.
Anyway...having owned both 2 and 4 valve Ducs....well..those 2 valve Ducs have some real grunt down low, makes them a lot more fun to ride irresponsibly on the street.
I had an ST2 that would consistantly loft the front wheel coming out of a corner near my house whereas the 4 valve Duc and the RC51 you had to really be in the throttle with the r's up to do that.
JohnnyB
PS. I'll be maggot lunch in 2035....I'll race you to heaven.