I would assume your Hyper .21 doesn`t have a pull start and needs a bump box to start . If so , you can`t just throw a pull starter or torque starter on the engine and go . Pull start engines have a special crank with a *** on it so the pull starter or torque starter can spin the crank to start the engine . If you have a non pull start engine you will need all what you mentioned above and a crank for the engine . You mind as well buy a new Hyper .21 engine that has the pull starter on it .