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No Spark

bennyblak

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Hello. I’m new to these forums. Do not know how to navigate so I’m throwing this out there. I recently bought an m.unit blue. Installed it on my K4 Cb750. Rewired the whole bike. Everything works BUT! I’m not getting any spark. Also, forgot to mention that I bought an Ultimate Pamco electric ignition kit from vintage cb750 site. I get my constant 12v to the pamco, get 4v out of pamco to coils. Nothing out of the coils for spark. Double, triple checked the rotor on the pamco to make sure that it was installed correctly. Double tripled checked that my wiring was correct. Even reached out to the company that supplied me with the m.unit, who btw also install it on their builds. They say my wiring looks correct. If anyone can help, pls reach out. Attached is my wiring diagram. I left the horn out because I have yet to install the horn. IMG_0625.JPG


 
According to your diagram you don't have 12 volts going to coils. You must have it at the coil plus to get the coil negative to work (Pamco greens). The black with white stripe must still be connected to coil plus sides.

Per Pamco instructions...............

'1. Connect the red wires from both cables of the PAMCO by extension to the Black / white wire from the kill switch that is connected to each coil. Alternatively, you could connect the red wires to another source of switched battery, such as the rear brake light switch or regulator to avoid having to remove the gas tank.'

It does NOT say in there that you remove the black/white from the coils. Although it seems to from the first sentence. But the way you have run it apparently.

Pamco is a simple inductive electronic, you run power to the coils at black/white and the Pamco then cuts them like the points did through the green coil negatives (old blue and yellow). It/s a basic transistor switch replacing the points. You do not ground the other post of coils, the setup is not CDI.

Try it that way and you should get it to work. You won't get a meaningful result out of measuring the green output (it being really an input), you are measuring a transistor leg that is not switched, it doesn't until the rotor is moving.
 
So the power does not go from the red wires, through the pamco, out the green wires, to the coils? The pamco is more of a switch? I have one of the primaries to ground on frame, the other primary to green from pamco. This is not correct?


 
It seems to me (if I’m understanding correctly) that you’re saying I should have another wire going from my ignition output to a primary terminal on the coil, and a green wire from the pamco to the other primary on the coil. And eliminate the wire I have to ground on frame that is on the primary terminal. Is this right? My start/kill button is wired to the input section labeled start on the m.unit. The m.unit distributes power to where it’s needed, it’s the brains of the bike. The buttons tells it what it wants and the m.unit delivers. I was afraid of burning out the coils if I wired it with 12v from the ignition. Aside from feeding constant 12v to the pamco.


 
You need 12 volts to the red Pamco wires and also 12 volts to the coil positives through the original black/white wires. The coil negatives go to the Pamco greens.

The Pamco has to have power to work. The coils do too. The coil negatives then go into the Pamco, when ignition key turns on the coils power up and as the Pamco sensor turns, the Pamco greens alternate switching off, every time one switches off its' coil fires. The Pamco is indeed a simple switch that replaces the points. Same as the transistorized electronic ignition used by the DOHC, the spark unit takes the place of the Pamco there. Look at a wiring diagram on the coils for those, the blue or yellow coil wires go into the spark unit to be grounded or not depending on the spark unit switching.

Don't be afraid of burning out the coils, they work on 12 volt. Like you said, eliminate the ground to frame you put on one coil primary, the Pamco controls that ground with the greens and how it fires coils.
 
Yes. Two primaries and two secondaries on each coil. Secondaries go to spark plug. There are no black and white wires on the coils, and the black and white wires (kill switch) original to the bike were replaced by the start/kill button the goes into the start input side of the m.unit. Either way, I found this (pic attached) on the web. So my wiring would look like what is in the pic minus the e-advancer and the kill switch shown being my ignition output? Is this correct?IMG_0158.JPG


 
I apologize if my questions seem redundant, but I really want to get this right. I worked hard on my build and so far it looks good. Thanks for your help. You are kind of helping me in understanding what was my gut feeling.


 
That pic should work, the red attaches to coil primary plus side and the green to the minus side. Other red powers up the Pamco. Kill switch should work too.
 
Amc49. I cannot thank you enough for your help. I wired it as such and now I have spark. Thank you so much for your patience and your input. You do not know how much I appreciate it. Btw, this is what my bike looks like. I still need to add the horn, change the chain, do the fork seals, and get the side covers. Thanks again for your help, truly a pleasure to have met you.
9bbac409a74e5730598f2e0af37f626d.jpg



 
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