I have a honda XR 125 which seems to be cutting out when warm. It starts on the choke and runs and revs fine for about 2 minutes then as I switch off the choke it cuts out but if I leave it on the choke it cuts out also. It like adding the throttle kills the revs. The bike sometimes makes a spitting noise which I suspect is a vacuum leak. Could the two problems be related? If not any other ideas as to what I could check?

Thanks in advance for any advice