I build Hybrid Rocket Motors that burn a rubber fuel grain with N2o as the oxidizer. Because they run off of N2o I can throttle them !!!
http://www.rockethigh.com
Great forum !!! Here is a picture of a 250cc Shifter Kart I built in the late 90's. It had a 4 bar and bearing rear with swaybar. I did not like the pipes that where available at the time so I built a custom one that went under the kart axle. I did not like the radiators so I mounted a core...