I love go-karts, I wonder when they were invented .
not sure, but I definitely tore around in them as a little boy with a small motorless model. in fact, I still ride them, but much more high powered versions!
Do you think they have variations of go-karts, like with different engines. 
definitely. you can have a four-stroke engine or even electric motors. sometimes I'll feel a little lazy and just ride around in a two-stroke
IT there an organization responsible for regulation for the different class of engines ?
Six-stroke engine
The term six-stroke engine has been applied to a number of alternative internal combustion engine designs that attempt to improve on traditional two-stroke and four-stroke engines. Claimed advantages may include increased fuel efficiency, reduced mechanical complexity and/or reduced emissions. These engines can be divided into two groups based on the number of pistons that contribute to the six strokes.
In the single-piston designs, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses
in many states. High school teachers know what they would like to do, but they have no time to do it. Yet we treat them as if we need to go and help them. In fact, I think we have much to learn from them. Until we come to the table with our high school colleagues, acknowledging them as the high-level professionals that they are, things are not going to change."
Stacy is also the author of the book Living by Chemistry, a research-based