I've had this same problem for about 3 months now and it's gotten worse.
I've been through all the electrics 10 times and everything checks out. I've got it worked out to this:
The bike starts first go every time. Once it is warm (sometimes 5 mins, sometimes 10 mins) it loses spark altogether. All other electrics are fine. All four plugs are dead (so not a bad coil).
If I cycle the ignition (turn the key on and off) I get a spark on closing (backfire) and it usually starts straight back up, often dying again moments or minutes later. Flicking the ignition on an off fixes it every time.
Usually the problem occurs if I am going up and down the revs. I rode home a long way a while ago at constant revs without it happening more than once. A spin round the block and open it up a bit here and there and it can die 4,5 or 6 times.
It's not the coils - they are newish and all 4 plugs are affected.
It's not the ignition switch itself. I have had it in pieces and there wasn't a sign of damage or a bad contact.
It's not a bad ground because I don't lose my lights, my dash lights or my starter/horn when the problem occurs.
Does a dodgy TCI behave like this?
