My 13 year old son and I just ordered a pair of 48cc engine kits. Weve been riding mini bikes for several years and Ive been on motorcycles for a long time but this is our first foray into modding our bicycles!! I'll try not to ask to many stupid questions and I promise to use the search option as much as possible!! Anyway I am hoping this is a lot of fun! By the way, why is everyone out of stock of the 66cc engine kits???