Not sure if a dirty carburettor may be the problem? It's not only old fuel that turns to muck. Modern fuels leave residues in all the wrong places. Hydroblast now offer a deep internal clean of your dismantled carbies using the Ultrasound process. For details and a short history of carby cleaning click on the 'Ultrasonic Cleaning' tab at the top on this web site. We're here to help.