A tilt switch to be carried by a motorcycle and connected in an engine control circuit to control the rotational speed of the motorcycle engine in response to the front end of the motorcycle lifting off the ground during rapid acceleration events (e.g. a "wheelie") to prevent the motorcycle from flipping over and causing injury or death to the operator and/or his passenger. Also connected in the engine control circuit is an on/off override switch that is located at the front of the motorcycle so as to be in easy reach of the operator. When the front wheel of the motorcycle is elevated with the override switch moved to the on position, the tilt switch will assume a closed switch condition to complete the engine control circuit. The engine control circuit then causes the engine speed of the motorcycle to slow such that the acceleration of the motorcycle will be correspondingly reduced, whereby the front wheel will automatically return to the ground to prevent the motorcycle from flipping over. With the override switch in the off position, the engine control circuit will be disabled regardless of the level of the motorcycle and the switch condition of the tilt switch carried thereby.