Since the amperage load during cranking drops the battery voltage somewhat, the bypass wire allows the coil to get approximately the same voltage while cranking as it does during normal running through the resistor. That's somewhere in the neighborhood of 9.5-10 volts, which assures a good spark while the starter is running.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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