what can kill an igniter on a 80 kz750e?

Been fighting with this bike since I got it. It was doing fine other than a little miss. Decided to give it a tune up. Changed plugs, plug wires, and air filter. After attempting to change the wires, I lost spark on cylinders 1 and 4. At first this only happened ar low idle. It eventually worsened until they wouldnt fire at all. Found a bad igniter. Still had no spark on 1 and 4 after installing another used igniter from a 650. Found frayed wires on the pick up coils. Replaced them with another used set. No change. Replaced the igniter with Lou's HEI system. Found a bad pick up coil.At this point, the starter button quit working so Ive been starting it by jumping the solenoid. Replaced the pick up coils with the ones that were originally on the bike and the bike ran fine for a month. Now its beginning the process again. It is losing spark on 2 and 3 this time. I am at a loss. The only thing I can think of is something is killing eithervthe pick up coils or the igniter or both. Any suggestions?

What kills electronics is voltage spikes. You could have a bad battery or a bad regulator but it sounds like something is putting high voltage transients on your system.

Another possibility is that using 30+ year old electronics is likely to keep finding bad parts.

Agreed.
Steve

If it turns out to be the pickups, you can combine 1/2 of each set to make a good set. The yellow/red wire pickup is the 2-3 pickup.

The igniters can get stressed if you disconnect the plug wires and check for spark without giving the spark a complete path for the current. That is, if you leave one plug wire unconnected while checking spark on the other plug wire, you are not providing a complete path. This can kill the coil or the igniter for that pair.

That is, if you leave one plug wire unconnected while checking spark on the other plug wire, you are not providing a complete path. This can kill the coil or the igniter for that pair.

Something I'm always mindful of when compression testing or other diagnostics.

Have you had an opportunity to work on the set up for then "new" version of the CBE-4 ignition modules? I made the mistake of getting them when I was setting up the hei replacement on this bike. Ended up finding a couple older models that worked to get the bike going but I still have the new ones. If a spike killed the replacement igniter, I wouldnt mind trying what you've been able to come up with for the new versions.

My head has been spinning as I'm going through and analyzing around 7 or 8 various HEI modules, both 4 and 7 pin, so my memory may be hazy. If I recall, the last partial test I did, I think I connected the pickup wires directly to the module. Blue to W, Black to G.... and Red to W, Yellow to G. I think this worked ok with the stock, electronic ignition coils (2.3 ohm Tec coils). You could try that and make sure nothing gets too hot. But you would be going into uncharted waters so I can't give much advice on how to avoid damage etc.

Based on how many new modules I'm finding that don't conform to previous versions, it may be a long time before I get them straightened out.