I fucking love those things. I swear I saw one the other day except it had dirtbike tires.
http://www.youtube.com/watch?v=6zuXSsDEzCk
http://www.youtube.com/watch?v=buga91RLVHg
I do remember someone saying that Kawasaki H1/h2 almost has the frame technology of a walmart bicycle, braking power of the flinstone mobile but it's all good once you hit the throttle.