could be the float is stuck and a little wrap will free it up.
vacuum has nothing to do with it... does it?  

Screwdriver handle,, rap, rap, rap,,
If thats a no go
fuel off, drop the bowl,, you can rotate the carb some in the bike.
Hopefully the assembly process went correctly and no junk got left in the float valve..
Did ya get that little screen out and clean it?
Eyeball the needle and inspect the sealing surface? and its seat?
Usually,, its the float, so, hopefully youll win it w/o taking anything apart..
If ya replaced the bowl bolts with allen heads then an allen wrench with the recesses carved in it to make it work like a swivel will whistle those bolts right out..