Need help finding spark

[Benmerk]

Alrighthere is a 1983 xs400 maxim and its having some spark issues. I had the bike fully running and driving just fine (except some carb sync problems) and I needed my battery on another motorcycle for a day so I took it off. Ended up forgetting my battery at home the next day so I tried to push start it with no luck. A few days later I put the battery back on and now I have no spark and I can not figure out why. The only thing I did in those few days was use a mig welder to tack on a seat pan on the bike. Now I've checked the ohms on my pulser coil, stator and ignition coils and they all seem fine. When I turn on the key I am getting 11.2 volts to my spark plug cables but no spark. I recently replaced the cdi box with one in better condition so I am not sure if it is that that is giving me the problems.
I occasionally get a dull spark but just one it two seconds of it only on my right coil,I think it's my primary one because it has 3 wires going to it unlike the left one that has 2.

Any Imput into helping me find the spark would be greatly appreciated.

 

[16VGTIDave]

When you say you are getting 11.2 volts to your spark plug cables, where exactly are you measuring this? The terminals on the coils? 11.2 volts is low, is your battery fully charged?

Based on your description, it sounds like the TCI module is dead or dying. Do you have the original TCI module? If so, reconnect it and test after you've charged your battery. Be sure to NEVER operate the ignition unless the spark plug wires are properly connected or grounded. The spark will go somewhere, and it can fry the TCI module if it can't find another path.

MIG welding with the battery removed should not cause a problem, but...

 

[Benmerk]

That 11.2 is from inside the plug wire where the plug would go. When I crank it over it drops to 8-9v. And the battery is fully charged. Tci is that the same as my cdi box?

 

[BBS360]

Inside the spark plug cap? At the exact point where the spark plug would touch if it were plugged in?
I don't think any useful measurement can be read from that point. When starting or running those voltages should be up to 40,000V. More likely to destroy a volt meter than anything else if that's what you're trying to measure.

Have you gone through the resistance tests in the manual step-by-step? Both left and right ignition coils have a primary and secondary coil each. All four resistance readings need to be taken to determine if the coils are good.