Abstract: An ignition timing control system for an internal combustion engine cuts the ignition when the engine rotational speed is below a threshhold speed indicative of stall. On starting, the threshhold speed is set low. The engine speed is monitored, and a higher threshhold is set when the engine has attained a speed indicative of full combustion.

Abstract: An ignition system for four cycle engines generates a first pulse when the crankshaft revolves by a first setting angle from a base position. The second pulse is generated when the crankshaft revolves to a second setting angle which is larger than the first setting by the angle difference between cylinders. The third pulse is generated at the position of a third setting angle which is between the first setting angle and the second setting angle in the position of the crankshaft when the crankshaft revolves twice. The generation of the first and second pulses is stopped or inhibited during the generation of the third pulse, allowing the first pulse to fade away.

Abstract: An ignition apparatus for an internal combustion engine includes means for generating signals indicating when the crankshaft and camshaft of the engine have respectively reached predetermined angular positions, a command circuit for initiating and terminating ignition operation in response to these position signals, and means for establishing a first operating condition, following each camshaft position pulse, in which the ignition operation is enabled and a second operating condition, following a subsequent crankshaft position pulse, in which ignition operation is inhibited, to thereby eliminate redundant ignition operation and the attendant power loss and heat generation. The apparatus also includes a timer circuit which act to enable resetting to the second operating condition by the crankshaft position pulses only during a fixed time interval following each cam shaft position pulse, in order to ensure stable operation when operating at very low engine speeds.