This afternoon I went for a test ride staying near home ( I live in a polder with long strait roads) to see if I would get the same error like a week ago. Kept the revs in the high range and yes after some 15 minutes the engine just stopped so I had to park it, glad it wasn't a highway though...
At first it starts to run rough with almost no reaction on the throttle , it does still accelerate somewhat though, but after 2 minutes running rougher all the time it just stopped. I felt the exhausts and #1 was stone cold, 2 and 3 were hot and 4 was somewhat less hot. This does point to an ignition problem, I'm using new ignition coils but it wouldn't surprise me if I have a flaky one
After cooling down for a 10 minutes or so the engine started again, #1 exhaust hot but #4 cold initially. Drove to the next exit and the roughness was completely gone. Was able to ride home without any issue
Next will be a test in my garage, applying some heat to the left coil and see if I can reproduce the problem