1980 KZ750

I suddenly dont have the same power in engine as before. I touched the header pipes with my fingers with spit on them and only cylinders 2 & 3 were hot, cylinders 1 & 4 were warm. Pulled the spark plug wire out of cylinder four, and she ran the same. Put a new set of plugs and still the same problem. How can I tell if ignition coil needs to be replaced or the spark plug wire need to be replaced? I have a meter. Thanks for any help I can get. Mopguy in Toronto.

One quick way is to swap the coils temporarily. If the problem moves to the other 2 cylinders it's the coils, wires, or caps. Ed

I think I literally tested EVERYTHING in the ignition system recently to get my bike running properly again. If you want to read through my thread while waiting for replies, it may help you track down the issue, but if you have a points ignition system, it may not:

kzrider.com/forum/4-electrical/465649-23...f-the-time-resolved-

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Would assure the coil for 1/4 is receiving full battery voltage via red wire to its primary winding.

Good Fortune!

A break anywhere in the secondary loop prevents either spark plug from firing.

Another possible scenario:

Thanks a lot to all of you. You were a great help.