Then at the start of July I started it up and as usual, first or second kick it fired up and as usual, good crisp revs. Set off down the road, got about 100 yards and it started to splutter badly, then it died. I tried starting it up and after a couple of very spluttery revs it died. I pushed it back home and from then it hasn't been on the road since.
I've changed everything and I mean everything. plugs, plug caps, HT leads, CDI's, Stators, Ignitions, Carbs, petrol tap, petrol, petrol cap, even put the old Mugello 225 on for a change.

There's a consistant spark, a good one. If I get it to start it won't rev, really poor revs for a about 5 seconds then dies. Constant kicking over or bumping and it sometimes tries to fire up, but won't. The choke works properly (Darrell Taylor Headset lever).
Took the loom green wire out of the CDI, nothing.
I can't ever remember having a problem like this that wasn't solved. I'm completely lost.