Erratic tickover T5

[sleepinghorse]

T5, standard spec, in good order generally now has really high tickover revs but manages to run ok. Carb and jets not loose, throttle cable not snagged anywhere, obviously I've adjusted the tickover screw to where it sounds fine but once you blip the throttle it revs like mad and takes a long time to settle back to idle. If this was my lambretta, I'd say it was either an air leak or I was running it too weak. It's factory spec, so wtf? Any ideas anyone? Not sure if I'm going to break it by riding it as it is plus it's stressful sat there at the lights with the thing revving it's b@11@x out!

[Juan]

I'd look at the flyside seal first. With some luck it'll only be the seal as they're prone to go there and hopefully the bearing hasn't yet decided to spin in sympathy.

[Jack221]

Have you checked that the mixture screw hasn't fell out? Or the pilot jet is not partially blocked? I would'nt ride it until its sorted

[acko]

Drop the gearbox oil and see if it smells of petrol. Main seal gone?