Re: What more can I do (please read)
Shift kit won't get you any faster than a 32t sprocket anyhow.
By Redline, do you know what revs your doing?
With a standard motor you may get a slightly better top speed with a slightly larger sprocket, but more revs. your top speed sounds about right for a standard motor, to get even close to 50 MPH, you will probably need either a better motor or port job, hi compression head and expansion chamber. Even then, unless you get everything spot on with a well balanced crank, your looking at about 45 MPH tops.
50 MPH will be over 9000 RPM.