coil wiring question

So am working on the bike and I notice that one of the wires that leaves the coil to the kill switch was unplugged (yellow and red wire). I plugged it back in and tested the starter, I got nothing, I unplugged and the starter turned again. I then unplugged both coils and tested each one, one side seemed to work fine, the side that was pugged in initially, the other coil was nothing. in all of configurations, the kill switch did it's job. any idea as to why this is happening?, is it harming the bike? as usual any and all advice is welcome.

With ignition switch ON and kill switch in RUN, the red/yellow wire is supposed to supply battery positive voltage to coil A and battery positive voltage to coil B.

Underneath the fuel tank, should be a red/yellow wire from the harness with a dual connector, and a separate red/yellow wire from the dual connector to each coil.

With ignition switch ON, and kill switch in OFF position, pushing on the starter button does nothing (supposedly).

Good Luck!

If your bike has the clutch interlock switch(clutch needs to be pulled or squeezed to work) it should do nothing unless the switch circuit has been bypassed.

Inside the headlight housing is where the interlock switch wiring will be found.

So I tried again and still nothing, I am pretty sure I don't have the clutch interlocking thing, because it starts in neutral with out the clutch pulled normally. i pulled the coil and noticed two cracks, one on either side, of the coating. I assume this is not a good thing, is the coil toast?

the other side

also the lower blue wire going into the handlebar switch was really hot

I'd say replace the ignition coils as any cracks will let in moisture possibly shorting out the coil(s).

Coil cracks can develope over time due to lack of cooling air and age. I usually have a fan running at full speed when I'm doing a carb sync procedure for engine cooling.

As for over heating wires, go through the many and various electrical connectors looking for signs of corrosion. If the connectors have green oxidation, then you will have higher resistance(which causes heat) with lower current/voltage capability in the circuit(s).

I use a very good brand of electrical contact cleaner/preservative called "De-oxit" www.deoxit.com
It's sold at Radio Shack in the U.S. and any other electronic supply store.

cracked coils need to be replaced..if age of wires and plug caps is unknown, may as well get them also....

If needed, there's a good color wiring diagram here on site.

In the green ribbon toward top of screen, point to KZ Information, then click on Filebase.

Then click on 1976 KZ900-A4.

Should then see and be able to download the wiring diagram.

Good Luck!

Here have mine for I have the exact same KZ....

Sorry if this is the wrong place for this....but I just got this bike and the PO had the two blue wires coming out of the rh switch plugged into each other. They are not connected as shown in the pic. I can't find them in the diagram I have and don't know where they are supposed to go.