first bike took me about 6 hours. 2 of that was the sprocket.
2nd bike was just switching over the motor after i broke the frame on the first one. took me about 2 hours.
3rd bike took 2-3 weeks, which was a rustoration, blueprinted and modified engine, all sorts of custom fab'd parts.
4th took me 2-3 weeks, and that was even more detailed. custom built copper tank, custom wheels, paint, etc.
the one i'm working on now is taking longer, 'cause i'm not really working on it. it's gonna get even more modifications than all the other ones so it'll take a little lnger, but once i dive in it should take 2-3 weeks, maybe less, because i have a real workshop.
on a side note, none of my bikes are ever really gonna be "done," unless i sell them.