Just to say what a wonderful sequence of pictures most inspiring.So looking at the barrel transfer ports is it ok to cut an Iron barrel the same I recall that this was a mod done on 8/e and 9/e villiers and ariel arrow?( dating myself I think Motorcycle Mechanics advocated this in the mid 1960's) What spark plug do you use and do you warm the engine on a different heat range ?For the non academic of us the pictures speak a thousand words, thank you.