Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Sounds like a stuck (closed) float on the carb that isn't filling. Try tapping with a spanner and see if it fills (releasing the float). Sometimes the floats hang on the rough cast edge of the pivot posts. I always lightly file the posts with 800 grit wet & dry when rebuilding which seems to do the trick.J