The book says the new 500cc Unit Construction Engine (UCE) motorcycles top speed is 82 MPH (132 kmph).
Now that my G5 is broken in it is totally happy and vibration free up to 60 MPH (97 kmph) but at 65 MPH (105 kmph), vibration starts to be annoying.
My bikes vibration doesn't seem to get any better at speeds up to 75 MPH.
IMO, these big single cylinder motorcycles are basically an improved 1955 machine but they share the same issues that were common back then (except they usually don't leak a drop of oil).
I should also mention that for the first 300 miles the Owners Manual recommends keeping the speed below 40 MPH (60 kmph). Then, up to 600 miles the speed can be increased to 50 MPH (90 kmph).
Over 600 miles there is no recommended speed maximum.