Hello again. I know the choke on a cold engine causes higher rpm but mine revs so high when the choke is on I worry its ruining the engine. When the choke is then switched off the revs are fine. It certainly isn't healthy for a cold engine to rev that high. Carb is a dellorto. All the inlet rubbers are new so i don't think its an air leak. Could the choke itself be worn causing this high revving. Carb has been stripped-down and rebuilt. Any ideas ?