Poor spark

[JohnT]

81 CB750P, won't fire on recommended new DR8ES-L plugs, but will with a colder DPR7EA-9 plug. Happens on all cylinders, so not thinking it is coils, maybe earths?
Can anything go wrong with pulse generators?

 

[plantguy]

81 CB750P, won't fire on recommended new DR8ES-L plugs, but will with a colder DPR7EA-9 plug. Happens on all cylinders, so not thinking it is coils, maybe earths?
Can anything go wrong with pulse generators?

Check your coil voltage on the positive side and at the battery. Read my reponce in this thread.

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

 

[brettp]

I don't know the answer to this question, so i have to ask. Will a hotter plug require more voltage fed to it to generate spark? It would make sense to me if the answer is yes.
And I would guess some bikes have a wider range of spark plugs that work because they can generate the voltage those all require. But I'm guessing here.

 

[mrtwowheel]

Those are resistor plugs, right? Why are you using resistor plugs?

 

[JohnT]

Those are resistor plugs, right? Why are you using resistor plugs?

The DR8ES is the NGK recommended for this model, and also what I have found in other searches, and the bike came with the DPR7EA's fitted, which is why I have them to compare. Thanks

 

[JohnT]

Check your coil voltage on the positive side and at the battery. Read my reponce in this thread.

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

Thanks, I'll get back to you as soon as I can do these checks.