Yes, it is a resistor. It limits the current to the coil. It is used to limit the maximum current in the coil, but the problem is that it also limits the current to the coil all the time. Coils take a small amount of time to reach their maximum current. The resistor limits what the maximum will be. Unfortunately, it also reduces the current when the coil is not at its maximum current.
A true ballast resistor increases resistance with heat. At idle, the resistor is at its hottest. That's when you want to limit the coil's current. It works ok, but the resistor is slow-acting.
A regular resistor can be used, but its resistance doesn't vary as much.
A better method is to use a variable-dwell-angle ignition and do away with the resistor. Kawasaki eventually did this with their early 80's (79 maybe) ignitions.
The ballast was meant to save wear on the points and helps keep the coil cooler at idle. With heartier coils and ignitions, you don't need the resistor.
Also, at startup, you want full power to the coils so often the resistor gets bypassed on startup or there will be a third tap on the resistor which provides less resistance during startup. I don't think KZ's use the bypass method, though.
Post edited by: loudhvx, at: 2005/12/10 17:22
