Bad TCI?

1982 xj750. Around 136,000 miles.
Has been running great. Last week went to ride to work. Bike cranked and cranked. After about 10 minutes and a few backfires it turned over and the ride in was uneventful. Ran a good 80mph on the freeway and never missed a beat. Went to start it up for the ride home (9 hours later) and again: crank and crank without turning over and a few backfires. Which sound awesome in the parking deck! After 30 minutes of trying I got it trailered home. I found that I am getting no spark. Had the ignition coils tested and they are fine.
Should I be looking at a faulty TCI? Not sure how to test it.
Thoughts???

 

There is no test procedure for the TCI. Yamaha tells you to diagnose the TCI by eliminating every other possible cause.

Your symptoms are consistent with low voltage to the TCI. While the starter will spin the engine over like mad with low voltage, the TCI falls on its face at around 10V. When you let go of the start button the voltage comes up and the TCI may fire off a plug. It might backfire or if you get lucky it actually starts when you let go of the button. Of course after you try to start it a bunch then check for spark the battery will be too discharged to fire a perfectly good ignition system.

You need to make sure the battery is fully charged, in good condition and all your connections are clean and tight before proceeding.

 

Sounds like the same issue I had with my TCI, although I would also get a couple of klms down the road and it would just die again. Replaced the TCI and never had any more problems.

 

Swapped out the original TCI with a replacement - still no spark.
What the heck could be left??