I bought me a Cushman

How fast do these things go?

Here's an interesting one...and reasonably priced-

http://tampa.craigslist.org/pnl/cto/4667088196.html

The Eagle we had would do about 50.
It had a cast iron 8hp single on it and a 3 speed trans right behind the motor with the shifter up on the left side of the gas tank.
One of the things that always intrigued me was the clutch mechanism on them.
In the picture I posted you can see that big section of bar sticking out on the side of the motor?
That is the clutch linkage (comparable to the shift fork on a car clutch)
That large wheel on the side is a centrifugal clutch and it has a big button in the center that when held down over rode the centrifugal and kept the clutch released.
If you held the clutch pedal down you could rev it up and it wouldn't move, but if you never touched the pedal you could stop and go just like a mini bike.
You could also hold the clutch down, rev it up and dump the clutch to do a nice burnout.

The "stomp start" feature was a trip also, but it worked very reliably.

Like I said above, ours had a 3 speed manual trans on it and it had a chain for the final drive instead of a belt like the picture.