So, the zeds been running a bit funny for the last couple of days. Today it went down to 2 cylinders - I limped into work and ascertained that it was a duff coil. Popped one of the ones off the original (z650) engine on and all is good.
Which lead me to thinking, how is it that knackered 30 year old coils don't appear to die whereas the (relatively) new and shiny ones from the bandit lump have given up without much of a fight?
baffling. Can't think of anything other than poor build quality which might explain it.