Actually, if someone re-geared the rear sprocket they could get to 160. Top speed is limited by red line.
If I was so fat and hat balls of steel, I could reach the max speed that, mathematically, is ~151MPH. Red line in 5th gear. Change the gear ratio either by few teeth on the rear or modifying the gear box, there is enough power and torque to get it to 160. Probably need a fairing kit as well for stability.
Could also do it coasting down a really steep mountain high way. Say, in Colorado.