1979 cb 750k RC01 ignition issues

[paulpenny6]

Hi, new to site, above bike off the road for 30 years, I have tackled all of the obvious issues, tank, carbs, service, etc. However having replaced both of the coils with new I am still only getting sparks on cylinder 2 & 3 but nothing on 1 & 4, checked leads plugs and some wiring connections. Seems this has come up before from what I have read but no conclusive answer. Condensor? CDI? points? I am used to older bikes so some of this is new to me. Thanks in advance for any advice. Paul

 

[brettp]

My 1981 CB750K had spark issues, too. Mine turned out to be spark plug caps and corroded wires. I suggest testing resistance and continuity from the plug cap all the way back to the CDI.

 

[Nylundarn]

Try swapping your CDI units around, see if the problem moves to 2 & 3

 

[plantguy]

I have seen a lot of posts like this one. My first thought is, guys prior to looking for answers on the internet learn how these systems are meant to work, get a good shop manual and a good meter. When the OP asks about the points, condenser I cringe.
Check my post in this thread.

https://www.cb750.com/threads/cdi-ignition-module.9296/