So from the looks, I doubt he broke 60...  and I had buddies with racing skooters that went 80+mph and were smaller than a razor scooter.  Those guys were nuts.
For the size though, that engine did sound nice and I dug the helmet cam.  Other than that...  my gokart me and my grandpa built when I was a youngster out a BnS engine riding lawnmower bored out that would do 35MPH without hurting nothing was the bomb...  

Not only did I learn to build stuff with my Papa, but I worked a paper route to buy the damn thing.  That's a real gokart.