Intermittent **** is a bitch! It won't stay broke long enough to find it. I would just pull all covers off everything and start wiggling every connector I could find. Sounds like it could be anywhere in the ignition from the key switch to something in the ECM. Intermittent sounds like it's being set off from vibration and then reset very quickly. Best of luck.

 

I am thinking you have an intermittent short to ground problem or a partially broken wire somewhere in the system. That is all I got. It just sounds like a wiring issue since it comes and goes.

 

I had the exact same problem. They could not find it on three different attempts to find the problem. Each time they said it ran fine but when I would leave to head home it started again about 10 miles down the road. So what it was is a broken wire behind the intake. When they would ride it and run in the shop if would not miss and buck because it was smooth roads near the shop. But when I would leave the roadway became rough and the vibration would separate the broken wire inside the casing. Forgot what the actual wire was for but it's behind the intake.

 

Didn't know what "TCA" was so I did a search. Lots of info came up and it seems MoCo has issued a related tech tip:

http://www.scribd.com/doc/55139820/2...ouring-TT418-1

 

That's what I came up with late last night..... same service bulletin, different site https://app.box.com/shared/x12e326mvi

 

Throttle Control Actuator - you found it I guess, but your description sounded like ignition cutoff not throttle.

 

That's what I thought at first too. But every wire from the TCA make their way to the ECM. That might be way it acted as though ignition was being momentarily shut off.

Life was so much easier when bikes had points......... You could fix your bike with a trip to the auto parts store. And if your battery was dead, it didn't really matter........ if you had a magneto, and a strong leg.