A control system for an engine includes a regulator with an output waveform which includes a plurality of waves, each wave having a peak portion, a first portion located on a front side of the peak portion, and a second portion located on the other side of the peak portion, the second portion exhibiting a more rapid change in voltage than the first portion. An ECU is configured to turn on a fuel injector of the engine at a first timing and turn off an ignition plug of the engine at a second timing, the first and second timings corresponding to a shift in waveform output from the peak portion toward the first portion of a first wave and a second wave, respectively. The waveform shift corresponds to a predetermined angular shift in the rotational position of a crankshaft of the motorcycle engine of preferably about 3°.