I started with the carburetor and found the manifold flange was damaged from over tightening, this could have been allowing the carburetor to suck air, because of distortion. The carburetor body needed to be replaced, and a friend I found off this site had a spare body for sale. I had to replace the jet block, because at some point someone had distorted its base by knocking it out, because as I was tightening the union nut it pinched the slide from moving freely. This sorted most of the spitting back, I then checked the timing was 3/8 before TDC and that was fine. It was annoying because on idle she would not settle evenly so I took the decision move the needle to make it run richer, as I noticed like you it would like a bit of choke. I then decided to check the valves and guides just in case air was coming through that way, I am glad I did as the inlet valve was not seated. I then seated it correctly and whilst the head was off found that I had a small amount of oil on top of the piston. I checked the taper ring on the piston and found it was upside down (the marking 'top' on the ring shows this) also making sure that the rings were not worn, by measuring them at the bottom of the barrel where there isn't wear due to the distance traveled by the piston. This is explained in the WDCO manual also, this solved my problems of spitting/idling and running through the main jet and needle jet. I also found I had an occasional backfire, and by putting a baffle from a beetle into the straight through exhaust (hidden) gave me back pressure, this has not altered performance and she runs like a dream now. I am not sure this helps, but I found this was a journey worth taking by learning about the machine I have grown to admire, and I am no mechanic. I found the help available by those in the scene/restoration invaluable, and I thank them all. :nut: