Righty Ho!
All very good guesses but not quite there.
I checked the carbs, inlets etc for a 2nd time.
Didn't touch the jets but checked the float and valve were good. And the CV rubber was sealing (bitch to get back on its wee seat!). And the breathing tube was clear. And the cables were good.
was the choke sticking on? Pretty sure it was fine, but thought I'd check the plug anyway.
****After all first thing I did after the lay up was put a new plug in...*****
The plug had been kept in my old garage. Which was a van.
When I whipped the plug out, the colour was very encouraging. But the gap wasn't!! It was tiny. 9 thou to be precise. Set it to the standard 35 thou, and all was well with the world.
I then looked at my dismanteld carbs on the bench and felt very stupid.
Morals of the tale:
1) It IS the simple things you have to check first.
2) Vans aren't good garages. Sometimes they're not very good vans.
3) Just because the part's been replaced new doesn't mean its fail-safe.
4) Lack of use kills (modern) motorbikes
5) I have still never had a case of bad petrol, or petrol blocking the jets!
Cheers all for your help. Much appreciated!
a