The International CBX Owners Association

Got a common problem on my CBX and CB750. Both bike have the same problem of #1 spark-plug repeatedly going dead during a ride. Could this possibly be a carb related problem? Help.

Check spark first and go from there.

That's my plan. Strange that it's on both machines #1. Perfect again when I change the spark plug. I'm wondering if not fuel related.

Ibiro wrote:That's my plan. Strange that it's on both machines #1. Perfect again when I change the spark plug. I'm wondering if not fuel related.

two bikes, that would seem to me just a weird coincidence.

I'm no electrical expert but if it was spark wouldn't plug #6 be affected as well, they both fire from the same coil. I guess you could switch the spark plug origins on coil #1, if the problem switches to plug #6 then it would be electrical.

my limited knowledge I'd suspect it's an air/fuel problem

Ibiro wrote: #1 spark-plug repeatedly going dead during a ride. Could this possibly be a carb related problem? Help.

what do you mean when you say "dead", is it fouled, melted ?

By dead, I mean the plug just quit working. Chased around the ignition system, nothing came up. Component test next.
I'm not sure, but can 1/2 a coil go bad and the other cylinder's side be OK?

Here is a easy check on that one. Switch the coil leads around. If it follows you got it figured out. It is not the coil.

Sounds like number one lead might be brittle and is 'separating' a little whenever you fiddle with it. Sometimes connecting and sometimes not. A kink could do that. Has happened to me before. Good luck.