A wire from the small terminal goes to the + terminal of the coil, downstream of the resistor. When the starter is engaged, full battery voltage is supplied to the coil, bypassing the resistor. The load of the starter running drops battery voltage down to a bit over 9 volts- - - -which is what the coil was designed to run. Sneaky, huh?
A word of caution- - - -with the bypass wire connected, the engine can start and run with the ignition switch turned off when the foot switch is engaged, unless a different ignition switch with an "IGN 2" terminal is installed. That's a wiring diagram change that was incorporated into the 12V electrical system that most folks don't know about.
Jerry
