The resistor is supposed to be wired in series with the ignition switch and the coil. It's there to control the current flow through the points and keep them from burning out while the engine is running. It's supposed to be bypassed with a terminal on the side of the foot start switch during engine cranking. Here's why- - - - - -
The normal output voltage of the charging system, either generator or alternator, is around 14.5-14.7 volts when running against a fully charged battery. During cranking, especially in cold weather, the battery voltage can drop as low as 10 volts or slightly less, due to the load the starter puts on the battery. To assure the ignition system gives a good spark during cold cranking, the factory installed a coil that functions- - - -you guessed it- - - - -at around 9 volts.
To keep the points from burning due to excessive current during normal running, they installed a resistor to drop the voltage at the coil to 9.5-10 volts once the engine gets started and the charging system kicks in. Unless the resistor can be bypassed during cranking (especially cold cranking) there won't be enough coil output to fire the spark plugs efficiently.
In about 3- - -2- - - -1 seconds, somebody is going to chime in with some advice to "run a coil with an internal resistor". Ignore them!
The resistor has nothing to do with cranking speed- - - - -that's controlled by the condition of the starter, the size of the battery cables- - - -and of utmost importance, the condition of the ground circuit from the starter back to the battery. All the cable connections, both from the battery to the starter, and the circuit back to the battery through the engine block and frame- - - -must be clean and tight. Don't guess- - - -disconnect and clean every connection, both hot and ground.
Jerry
