Abstract: A speed limiting circuit measures the speed of the engine through the use of a device that functions generally as a tachometer. A speed signal is provided and is a function of the frequency of a plurality of pulses provided by a pulse generator. The frequency of the plurality of signal pulses, in a preferred embodiment, is representative of the frequency of a plurality of voltage pulses provided by an ignition coil. Since the voltage pulses from the ignition coil are directly related to the speed of the engine, the speed signal from an integrator can be used as an accurate representation of the engine speed. This speed signal can then be differentiated to determine the acceleration of the engine. The speed signal and acceleration signal are combined by an adder and the combined signal that results is compared to a threshold magnitude.