750 twin electrical system

Does anyone know where I can find a manual to trouble shoot my starting circuit. Or for that matter what is in the starting circuit. Someone bypass the starter with some after market relay and now the kill switch does not work. I tried to connect is back with the KZ750 owners manual schematic, but new (previous owner) wires have been installed and I can't figure out what's going on.
I need the kill switch working when I go register the bike. Thanks.

By "owners manual" do you mean the actual owners manual that is carried under the seat, or the Factory Service Manual?

The wiring diagram in the Factory Service Manual is as good as it gets.

I intensely dislike people who hack vehicle wiring

What year 750 twin? I may have a wiring harness depending on year.

Yes, What year?

There might also be one here on-site in the filebase.

kzrider.com/index.php?option=com_docman&Itemid=108

Check here, for your year.

Welcome to the site by the way.

I have the service manual and the electrical diagram is just a one page oneline. Basically sucks. I tried hooking everything up the way it was but when I didn't I just about fried my something. Not sure what it was I think it's the starter coil...its uneder the gas tank. Anyway. I'll just try to keep on going with it. I was hoping someone had experience in re-wiring these bikes so I could get on a discussion with them.

Somebody bypassed the kill switch because it wasn't working properly. Probably had a bad connection and the bike kept dying. First thing to do is to take the kill switch apart and ensure that the top part of the switch is tight against the bottom part... there is a "bb" sitting in a detent that makes the switch click into place. You will need something to act as a shim so that the top part of the switch is tighter... that will keep the switch from losing contact.

Next thing to do is to look at where the wire comes in and goes to your starter button. This wire USED TO go into the kill switch and a short piece of wire came out and went to the start button. That is how I would bypass the kill switch... take the original wire that connected to the kill switch and connect it directly to the start button.

In general, the starting system isn't all that complicated. You have power coming from the ignition switch and it goes to the kill switch. It comes out of the kill switch and goes to the start button. When you press the button, contact is made and a wire comes off the button and goes to the starter relay (solenoid). This wire will generally be black. It is there to trigger the relay closed. Power goes to the relay from the battery... see the big thick red cable? On the other side of the relay switch is a thick wire going to your starter.

When you push the starter button, power from the ignition switch goes through the kill switch to the starter relay and shuts an internal gate. This allows power from the battery to go through the shut gate to the wire going to your starter. When you release the button, the gate opens and no power goes across.

I am not sure what color wire comes off the ignition switch and goes to your starter button but the wire off the button to the starter relay will be black.

Looking at the circuit it looks as if an after market relay was installed. I'm going to have to see what the heck is going on when I have some more daylight. It still gets dark quick up in ND.

If it will help i have most of the wiring harness from a 76 i am junking.you can have it for the shipping cost.

Wiredgeorge pretty much nailed exactly what I was thinking. I noticed your name is al_ndsu. Do you go to NDSU?? Just wondering because thats where I go to college and I have the exact same bike. I also have a decent amount of free time and intense motorcycle withdrawals when I'm out here away from home. So if you ever needed some help...

There is no reason to have a relay installed in the starting system since the starter solenoid IS a relay. The relay is most likely for the headlight or something else. I have seen the kill switch bypassed a zillion times because it gets sloppy and the bike will die when riding as a result. OPEN YOUR RIGHT HAND SWITCH GEAR to get to the bottom of this problem because it is highly unlikely that the black wire going from the starter button to the solenoid was messed with. Any mods to the kill switch are INSIDE THE SWITCHGEAR.

I had to search all your posts to find out what year 750 twin you have, thankfully you finally stated it is a 79 KZ750 twin in a new thread you have started

On the 750 twins and most other KZ's, the year/model does matter, they are not all the same.

You need to be looking at the 79 KZ750 wiring diagram because the 76-78 models are different. Kawasaki.com says they are the same, but it's wrong.

The ignition coil is under the tank, the starter relay/solenoid is under the left sidecover.
If you saw smoke coming from under the tank, then most likely it was your main wiring harness.

The simple way to fix this is to get another wiring harness, they show up on eBay occasionally, cheap. 79 would be best, 78 will work if you install a jumper wire to connect two wires together that come out of the main harness under the tank (wires to the light switch on the 78, 79 doesn't have that switch).

If you can't read the wiring diagram in the manual, don't even think about trying to make a new harness, if you can't read the wiring diagram then your chances of repairing the current wiring harness are slim.

Either learn to read the wiring diagram, or find someone to help you that can read it.

My current ride is a 79 KZ750 twin, but it's actually a combination of 76-82 750 twin parts, so I do know what works

I have 1 79 750 twin, 2 80 750 twins, and 77 and 78 disassembled 750 twins, plus a "bunch" of extra parts.

And four 750 fours stabled here