Even those little bikes with the 50cc weed whacker motor can be pretty un-nerving...my neighbor has one of the made-in-china pocket bikes and after the silly plastic "stop" on the throttle was removed, it winds out to like 32-33mph- pretty fast on 5" rims and a frame with some very questionable welds. Stability is about as good as a Vmax at 140....
My "miniMax" will hold about 40mph decently, but cornering at that speed on pavement with super knobby tires results in major "walk" in corners, so you have to waaaay oversteer to not end up in the ditch.
I really can't imagine something that small with such a short wheelbase making it much past 40 or 50 before a moose fart in Canada induces some instant death wobble, and you get a tattoo of the engine's cooling fins pressed into your leg.
Probably slow as anything off the line....it'll just burn out the instant you apply any gas....