Quote Originally Posted by pete376403
I once had a similar problem on a CB750 Honda - power would cut for no apparent reason and then come back, just as mysteriously. Turned out to be a bad wire in the loom at the steering head. ( nearly all the wiring connectors were in the headlight shell, so nearly every wire ended up there) The wiring flexed with turning the handlebars and sometimes would fail.

With the bike on the stand, try flexing the wiring loom with the motor running, wriggle connectors, tap electric boxes (gently), see if you can make it fail.
Thanks, I have tried all of that, and had no success either, I'ts a bit of a puzzle, took the old girl out again today and all was well, this intermittent problem can be months apart and of course every time you do something like clean contacts or crimp wires tighter or something you imagine you have fixed the problem only to have it play up again 2 weeks later, I think it's menopausal