Thanks for your responses. Its running rich because after a run the plug gets covered in soft black sooty deposits. If the bike does not start first or second kick the plug is soaking wet The choke is not sticking, I have completely dismantled the carb and cleaned it thoroughly before blowing everything through with compressed air. I have checked the needle, the choke and the cut-away which has not been tampered with. It just seemed to me that having the needle in almost its highest possible position was a likely cause of richness and I wondered whether the Haynes manual had got it right.