(embarrassed)
I've carefully rebuilt my 627B carbs with new o-rings from BryanJ. They're OK and definitely better - but there's still a hesitation when pulling away at 2000-3000 revs.
Now, looking carefully at the diagram in my Haynes manual, I see that there's ANOTHER JET!! (oops)
I've read around TT and BryanJ on removing these and the general consensus seems to be that they are driven out with a wooden drift. The question is - has anyone ever done this ??
Experience please.