TOPIC:

I own a 1976 KZ900. 4 years ago I installed a new electronic ignition. It ran fine for two years, not a mishap. Then one day it started to cut out on one side (1&4) and the fun began-testing coils and pickups and wires, even swapped coils around to see if it went to the other side and it did. I replace coils and wires and electronic ignition and it did not solve the problem. So I put the old point set back in and the bike ran great once again, problem solved, I thought(PS the new electronic ignition was tested by the manufacturer and was said to be OK.
A year later with the point set still installed,the same thing started to happen again. I would lose one side. This has to be something easy. There is not much to an ignition system. Where could my problem be? I love this old bike but everyone says to buy a new one and save myself a headache.

Would first attach plug caps to four brand new NGKB8ES plugs with bases held against the engine, and inspect spark quality while cranking.

Is there good fat spark on each plug?

Good Luck!

sounds like a bad connection, when you changed things back you got a good connection, now it is loose or corroded again.

clean all the connections and check voltage.

battery
integrity of wires and connections
point surfaces
condensers
ignition step up coils
resistor spark plug caps

you had 1 type of problem a year ago.

this year it might just be a condenser, they'll burn up before a coil will.

Well, we checked, cleaned, and refitted most connections, including under the headlight. Reset the points-yes they're a bit worn. Replaced a fouled plug, tightened up the ignition switch, checked fluid levels in the battery. Discovered and fixed some worn or loose connectors. Fired her up with the gas tank off and heard a lot of static-like something was arcing. Removed the coil wires and refitted them. Checked the spark plug connection. No arcing but still the one side was out. Switched the coil wires around-still the same side was out. Went to check the coil(these were installed last year). Started her up again and the arcing noise was there once more.
Upon closer examination we noticed that the bolt that holds the coil to the frame was touching the screw that goes into the coil. Put some distance between the two and voila!-all four are back in business. We are going to try to replace the metal spacer that fit over the bolt with some insulating material and see if that prevents the arcing.

great job

Some clear RTV compound will work to keep corrosion off the primary connections and still allow removal for maintenance.