BufoBolt
Husqvarna
AA Class
Hi all, thanks again for your comments. Finally getting to the bottom of this and its all starting to make sense. 2premo's explanation to what is happening with the plug seems to fit. For one thing the ignition was slightly advanced. Shutting off the (leaking) fuel valve did appear to make it worse. I'm also inclined to agree that although there are a lot of revs, there is not much power/ load behind it. The throttle slide was not that far off the bottom of the carb. Stalling with the bike in gear and brake on did not occur to me but would have been the way to go. Followed by flipping the clip on the float bowl of the Bing (i have the early type without choke). I will know for next time..... Kris