I read somewhere where you can modify the clutch or carburetor to increase the speed of the Tank Urban Sporty model. Right now it max out at about 40 mph downhill. What can I do to get that 60mph that everyone says it can do?

I'm not sure about modifying but the reason you top out at 40 mph is probably because you have the the "sporty 50cc" Where as "the sporty 150cc" tops out at about 60 mph