Thanks Blumbly but I had the cylinder honed and fitted new rings, bearings and seals when I had it down. The cylinder was a bit scored but the professional hone brought it up pretty good. The engine re-manufacturer who I used was an old experienced chap and he was happy with the job. Having said that, I never actually mic'd the bore to check for wear. The massive increase in fuel consumption lead me to think that the carby may be flooding despite the new needle that I installed?
