i have a slightly different opinion on 4strokes then most.
IF you think you have to have one, get a used raptor 700, find it cheap.
Take the fucker apart, get the head ported, 5mil stroker, bore it to a 770,
get a dyna ignition, dual exhaust, bolt it back together and take off. They run very fast, reliable, and all that work is pretty inexpensive. In my opinion you got the 2nd worst 4 stroke sport bike made.