OK... over the weekend I adjusted the carbs and went for a little drive and I have eliminated totally the sputter. It was the leaking jets that obviously messed up the fuel supply and the engine was just sucking air at the higher revs. Thanks for all the good advice. I think noticing that the hose to the jet was wet with gasoline (petrol) really was the giveaway hint to the problem. I changed the spark plugs and noticed one wire was a bit loose to the plug. I did get some sputtering tiny backfire pinging at times. Could the loose plug have caused that?
Learning all the mechanics is good fun. I have been watching a lot of Moss Motors and University Motors Youtube videos.
