CBX Z Ignition power Circuit

[Little mate]

Just found a melted connection from alternator to rectifier so will have to cut wires and do a splice. Then pull the alternator and check for bad windings. Is the 81 rectifier the same as the 79 if so I will have to dig thru my attic or a 79 cb750 I have 1 of those somewhere.hope I can find igniters while I'm up there along with a set of pickups for the pulse gen

[Little mate]

No luck on the regulator /rectifier both the spares did not test good, that is if the test in the manual for the 2000ohms and 50 ohms is a good test all I got was around 500 or so on all three regulators / rectifiers red and green wires are all three bad ? It looks like it to me

[Little mate]

I have question we know that the alternator does not putout at low rpm, but does it have output while cranking at startup.

[RC 166]

On the first page of this excellent topic I see Aris' modified schematic with the relay feeding power directly from the battery to the spark unit.

I have a question about the black/white cable going in/out from the spark unit:

What is it doing there? Is it just a power bus, delivering power to the igniters and such and then carry on to the coils, or something more complicated? If it is only power delivery, I plan to branch it at the relay output to get a direct shot both to the spark unit and the coils.

Here you can see what I mean.

CBX '79 Ignition power cirquit crop.jpg

[pmcburney]

Yes, it's a bus.

How you distribute +12V to the coils is up to you, but given the small distance between each coil compared alternatively to the three much longer leads required from the relay to each coil, it makes sense (well it does to me) to just dimension the the 'bus' according to the voltage/current requirements and wire it as a far neater and more compact method, as above.

But, you do you.

[RC 166]

pmcburney, Thanks for the answer.

Now I know it is just a power bus and it is probably built like that because of some wiring architectural reasons.

Well, what I meant in the first place was to go directly from the relay output to the coils as opposed to just dump it into the brown connector to the ignitors pack and then through it to finally end up at the coils.

God knows what happens in the pack through any splices and what not before it arrives at the coils.
Of course I will change the ribbon cable (3 wires from the ignitors to the coils) to something beefier. The cables on the ignitors pack will be left as they are. And, of course, the whole power chain from the battery-fuse-relay to coils will be heavier than OEM!

Yes, I will stick to my plan, but leave the ignitors pack with its pigtails as OEM. At least I have done a healthy upgrade of the system.
Looking at the OEM ignitors pack etc. made me decide to install IgniTech anyway in future.

20250221_093705crop.jpg

[pmcburney]

Fair enough - any wiring upgrade from stock is a good thing.

Yeah, I have replaced my ignitors (and mechanical advance) with an IgniTech ignition.
It has it's own separate +12V feed from the original marginal feed through the kill switch, which then also switches a direct +12V feed from the battery through a relay to power the coils.

I didn't run separate feeds to each coil, just a single feed from the switched side of the relay which is then 'jumpered' across to the subsequent coils as per the original OEM ribbon cable.
There's no voltage drop from the battery to any of the coils.

I decided this was the most practical arrangement of the wiring as there's already three coil signal feeds that run to the coils - another three separate coil power feeds was going to make things untidy and take up more room in already crowded area.

This seems to work well for me - the bike has a very smooth and strong pull of torque from anywhere and without any hesitation, and I heartily recommend the IgniTech unit.

Let us know how your install goes.

[RC 166]

pmcburney wrote:

"I decided this was the most practical arrangement of the wiring as there's already three coil signal feeds that run to the coils - another three separate coil power feeds was going to make things untidy and take up more room in already crowded area."

Please post a picture of your setup. I think we already agreed that the power feed from relay to coil1 is a single wire and then jumpered to coils 2 and 3. Then there must be 3 separate wires from each coil (-) side to the ignitors (the ribbon cable).

[pmcburney]

Oh yes, there is, that's unavoidable.

I may have misread your post, my apologies...
I thought you were wanting to do away with the ribbon cable and run three separate +12V feeds to each coil as well as the three signal feeds - six leads in all from the ignition and relay to the coils.

[RC 166]

Thanks pmcburney!

Well it is easy, (don't ask). I try to keep writing short and support with pictures most of the times. I hope my schematics was clear though.
That's the one I will stick to.

My main objective was really to get information about the power into the ignitors. Thanks for that info!
Now I know that I can shortcut from the relay straight to the coils, which I think is an important update of the "relay mod".

Anyway, we are back on track....