Update : So, she has started to leak petrol rather badly from the carbs. Upon investigation, it seems when I stripped the carbs, I omitted to fully tighten the float valve seats properly - DOH.
Anyway, on the driveway this morning, I managed to pull the float from the RH carb, and tighten the seat, however, the float pin is extracted from the right, and the left carb has the right carb up close. So no-go on the left one. (sorry, do you follow me ?).
Tonight, I found the time to remove the rubber inlet manifold, (now rather perished on the carb end - damn!), and the battery tray, so could get a tiny spanner on the left hand float seat whilst the float was still in situ. Hoorah ! I had promised to pick my son up from his Scout meeting by bike.
Put it all back together, connect the fuel hose, switch on, and, yes, petrol still pours from the left carb.
I seriously contemplated tossing a match at it and collecting the insurance money !
Anyway, she now sits at the back of the workshop in disgrace whilst I try to summon the will to get the carbs off again.
And I collected my son from Scouts tonight on a BSA A65.
Which gave me no trouble at all .