Spark plug wont stop firing.

[will e.]

This one has me stumped. When I hit the starter I'll get one normal spark and then the plug "dumps" one big constant spark. Does this on both 4 and 3. First thought was bad points or bad wires leading to the cdi boxes. Tried swapping out the points with the same result. Pulled the wiring harness and checked continuity to every other wire. I ordered a new set of coils to see if swapping them out would do the trick but they haven't come yet. I've had coils fail on me before, but never two at the same time. And I doubt that's the problem. Anybody ever see this before? Any advice on what I might be overlooking?

[Re-run]

What points, you shouldn't have point. Do you mean the ignitors? The ONLY way a coil is going to fire is if it has power going to it that gets interrupted. A coil is nothing more than a transformer. You feed power to 1 side of the coil. When the power is cut, the electrical field drops and induces current in the other side of the coil which then goes to the plugs. So, something has to be allowing current to the primary wire winding, and then cutting it off so that it drops. It is virtually assured that your ignition unit is to blame. Honestly, with as weak as these unit become over the years, you might have better luck getting an aftermarket ignition.

[TOOLS1]

What do you mean by "dumps one constant spark?" I am going to guess that it is backfiring, and you have the plug wires swapped between 3 and 4.
TOOLS

[shinyribs]

 Like Rerun said, you don't have mechanical points on a twin cam. Your have a pulser ( on the end of the crank) that feeds the signal to fire to the coils. You also have spark units, which are basically little CDI boxes to help boost the spark energy.

Inside the pulser is a magnetic switch that operates like a set of points. When the tip of the ignition rotor passes by the pulser it causes the magnetic switch to close, and that is what triggers to coil to fire.

The only thing I could imagine is a stuck pulser, and that would be a pretty odd thing. There's an air gap clearance that needs to be set, but an improper air gap would lead to no, irregular or weak spark. It can't really lead to a continuous spark, but the FSM will show you where to set the air gap to rule out that possibility.

It may be possible the one of the spark units ( CDI's) is faulty, but as I dont fully understand how they operate I cant even begin to diagnose that part of the system. The FSM might be your friend there.

Good luck, and let us know what you find. This is interesting.