CDI Question

Hello again friends. I've neev driving myself nuts these last couple weeks trying to "understand" the BS that is the electrical. I've reached another hiccup. I've provided the wiring diagram for my bike; working on the CDI currently. Now, I replaced the stock start buttom/killswitch combo with a cheap china one for the time being (until i can afford something nice, and after its running). The new one that I have has a separate starter button and a toggle engine stop switch.

If i were to use the stock switch, it's easily color coded to match up using the wiring diagram, but since i dont have a separate diagram for this new switch, I'm a bit stuck, because I cant actually make sense of the relationship between the CDI, the Ignition, and the killswitch/starter button in the original diagram. I understand how the starter button operates, but it looks as though, in the diagram, the CDI, IGN, killswitch, and starter button are all connected. And i've tried google-ing answers, but every circuit I find is different.


Put simply, I need three things;

Can someone explain how the original stock switch is wired to all of this stuff (be as detailed as you can please) before I lose my wonderful full head of hair? Can someone explain how I would go about wiring this with my new switches? And lastly, can someone explain the circuit the CDI fits in? Honestly, it's not connected to the battery, stator, or the R/R. so I'm not even sure how the thing is powered. Understanding what's at work will help me greatly, as I'm someone who simply can't settle with 2 + 2 = 4; I need to know WHY.

Thanks much everyone in advance.

Firstly, that Kz750 twin does not use a CDI ignition. Websites will often have them mislabeled as CDI, but they are not CDI. Only a very few Kz's actually use CDI. Your bike uses a transistorized Kettering ignition. It may be abbreviated IC igniter, or called a transistorized ignition. It's important to know this because CDI and Kettering ignitions connect to the kill switch in very different ways. In a typical CDI ignition, the kill switch is used to complete a circuit to ground to stop the motor. On your bike, the kill switch stops the motor by removing power from the ignition.

On your bike, battery power is routed to the ignition switch on the white wire from the main fuse. Then the power goes to the kill/starter switch through the yellow and yellow/red wire. From the kill switch, power continues on toward the coils and IC igniter through the red, and yellow/red wires. The IC igniter is grounded through the black/yellow wire. The coils ground through the IC igniter on the black wire and green wire. The starter button sends power to the starter solenoid through the black wire (when you press the button).

So you don't really need to worry about how it connects to the stator, reg/rec, and battery. Those things are for the charging system. You can use the main fuse as your starting point for power. Obviously, the ground for the ignition does go to the battery's negative terminal.

Without any info on the aftermarket switch, it will not be easy to help hook it up.

If you have two of something, and then you get two more, if you count them all, you will see you then have four of them.

loudhvx wrote: Firstly, that Kz750 twin does not use a CDI ignition. Websites will often have them mislabeled as CDI, but they are not CDI. Only a very few Kz's actually use CDI. Your bike uses a transistorized Kettering ignition. It may be abbreviated IC igniter, or called a transistorized ignition. It's important to know this because CDI and Kettering ignitions connect to the kill switch in very different ways. In a typical CDI ignition, the kill switch is used to complete a circuit to ground to stop the motor. On your bike, the kill switch stops the motor by removing power from the ignition.

On your bike, battery power is routed to the ignition switch on the white wire from the main fuse. Then the power goes to the kill/starter switch through the yellow and yellow/red wire. From the kill switch, power continues on toward the coils and IC igniter through the red, and yellow/red wires. The IC igniter is grounded through the black/yellow wire. The coils ground through the IC igniter on the black wire and green wire. The starter button sends power to the starter solenoid through the black wire (when you press the button).

So you don't really need to worry about how it connects to the stator, reg/rec, and battery. Those things are for the charging system. You can use the main fuse as your starting point for power. Obviously, the ground for the ignition does go to the battery's negative terminal.

Without any info on the aftermarket switch, it will not be easy to help hook it up.

If you have two of something, and then you get two more, if you count them all, you will see you then have four of them.

I appreciate the information. It was incredibly helpful - thank you! Now that I understand the flow of electricity, I'll easily be able to install the new switch. I'll splice the yellow power wire from the Ignition switch into two wires. The start button connects to the power (yellow from IGN) and black from the starter relay (bypassing the clutch switch). The killswitch will be wired with the other yellow power wire, and the yellow-red that connects to the coils and "IC" igniter.

OR instead of splicing the yellow wire into two, I could simply run it to the killswitch, and run the yellow - red (to IGN system) and the black wire (to starter relay) to it, with the starter button somewhere along that black wire. That way, if the killswitch is engaged, the starter nor the coils can receive power.

Seems like you got it. From the factory, the kill switch is wired to disable the start button, but it can easily be rewired so you can power the starter without ignition, so you find many bikes configured that way. But people often forget to check the kill switch when the bike fails to start, so just remember to check if you do wire it that way.

loudhvx wrote: But people often forget to check the kill switch when the bike fails to start, so just remember to check if you do wire it that way.

Yeah, I'm definately one of those types. I'll probably go with option "B".