I've been using it for nearly an hour this afternoon Slight carb readjustment once it had settled, but nothing really.
It's been fine.
I suppose I've been messing about with engines on and off for nearly 50 years now, and that's only the third or fourth time I can remember something similar, that is an engine that seems to start and run OK but stops after a while.
Had a couple of blocked fuel cap vents, that Mini thing with the fuel pipe, and a duff coil (on a Mini again IIRC) that was failing when warm.
I wonder if this time it's our "old" friend ethanol. Here's my theory. Ethanol had evaporated, leaving 10% less fuel thus making the oil mix more than it should be. Hence causing the engine to run weak until it overheated and stopped due to fuel vaporisation.
I thought (with hindsight) that it was smokier than usual.
John might remember the dire warnings in "Motorcycle Mechanics" back in the day, about using richer oil mixtures than recommended in pre-mix 2 strokes due to the engine running weak.
If it was that, then it confirms my feelings about pretty well all the "green" solutions on offer. I'd rather use vehicles etc. 10% less than have something added to the fuel that causes all sorts of problems.