Thanks Rob, Yes, I believe the spacer method would work equally well. I just got a 100mm M10 bolt and screwed it in, popped straight off.
Well, I changed the generator side seal….. No improvement, so I got myself a clutch puller and an engine locker and changed the clutch side seal. Guess what…. no improvement.
I will revisit the carb and manifold, although I thought I had been pretty thorough the first time. Perhaps I will try a different carburettor if I can get my hands on something that fits. The only thing I can add is that by trial and error I discovered that if I drop the throttle needle right down to it’s lowest position (top notch – weakest?) then it will run at a lower tickover (2000 rpm) but still if I blip it revs up and takes ages to settle back down to 2000.
At least I have eliminated the seals as the cause, I know I have a good set of seals in and I won’t feel as daunted at tackling the job on other bikes in the future.