Cb750 m unit ignition wiring

[Biggerthanbikes]

Hi everyone, new here and looking for some wiring help. I have a 1980 cb750 and am in the middle of a m unit install. I have it 95% done but can not seem to get spark. All the diagrams I have seen just have one wire coming from the ignition output on the m unit to the coils. I have 3 wires coming out of the coil. Blue, yellow, and black with white stripe. I have tried every combination of these to try to get spark but nothing seems to work. The coil is grounded and the bike was running before I stripped it down so I know my coils are good. Any input would be very helpful. I have tried looking at stock diagrams but I am not super knowledgeable when it comes to wiring. Thanks

 

[Nylundarn]

Did you find a solution? I rewired my bike last year so maybe i could help you.

 

[les49]

Did you find a solution? I rewired my bike last year so maybe i could help you.

You might be able to help me. I have a 1980 CB750 R

I removed the "spark units" Not the ignition coils. it has been a couple of years and
I cant remember where they were bolted to the bike. They have a mounting plate about an inch square and are on short length leads. I think they must mount to the frame rails just behind the battery but not sure

Thank you.

 

[brettp]

You might be able to help me. I have a 1980 CB750 R

I removed the "spark units" Not the ignition coils. it has been a couple of years and
I cant remember where they were bolted to the bike. They have a mounting plate about an inch square and are on short length leads. I think they must mount to the frame rails just behind the battery but not sure

Thank you.

Yup, that's where they are originally.

 

[Nylundarn]

You might be able to help me. I have a 1980 CB750 R

I removed the "spark units" Not the ignition coils. it has been a couple of years and
I cant remember where they were bolted to the bike. They have a mounting plate about an inch square and are on short length leads. I think they must mount to the frame rails just behind the battery but not sure

Thank you.

This is the best pic I found from when I restored my CB750 KZ 1979, they have since been relocated and replaced with the marktronics alternative. Hope this helps.

 

[Nylundarn]

You might be able to help me. I have a 1980 CB750 R

I removed the "spark units" Not the ignition coils. it has been a couple of years and
I cant remember where they were bolted to the bike. They have a mounting plate about an inch square and are on short length leads. I think they must mount to the frame rails just behind the battery but not sure

Thank you.

Sorry it looks like yours could be different, you should look up your model year on CMSNL.com

 

[Tronco]

Hi everyone, new here and looking for some wiring help. I have a 1980 cb750 and am in the middle of a m unit install. I have it 95% done but can not seem to get spark. All the diagrams I have seen just have one wire coming from the ignition output on the m unit to the coils. I have 3 wires coming out of the coil. Blue, yellow, and black with white stripe. I have tried every combination of these to try to get spark but nothing seems to work. The coil is grounded and the bike was running before I stripped it down so I know my coils are good. Any input would be very helpful. I have tried looking at stock diagrams but I am not super knowledgeable when it comes to wiring. Thanks

Hi!

I also installed a M-Unit (blue, in my case) on my Cb750 rc04.
Did you still have the CDI’s on your wiring? Because you need them… I have never found a diagram for the m-unit without them.

I don’t know if I can help you, or we can help each other because I still have an issue with it, only are firing cylinders 1 and 4, and even with new coils, so probably I need new CDI’s.

We can share our diagrams to try to find the problem. (If in your case still that problem, or maybe you solved already)

Thanks! See you