A mini motor bike for chidren is powered by a 4 hp single cylinder gasoline engine governed to run at a maximum of 2250 rpm and idles at 560 rpm. A 5.5 inch centrifugal sheave actin as the clutch, is mounted on the engine output shaft. Design a v-belt/chaon drive which limits the top speed to approximately 17 mph. The outide diameter of the drive wheel is 14 inches. A jack shaft, which rotates freely on bearing mounted in a housing transfers the power from the belt to chain.