I called John Gillard the other day, he says it’s carburation. He agreed to sort it out, so my carb will be making it’s second transatlantic journey. Regarding aftermarket air filters, I went to a hot rod shop here and they do have a unit that will fit on the end of the long cylinder so I may eliminate the felt and have a modern filter. It may look odd but at least it will work and hopefully there will be less intake noise. I need to measure the space in front of the cylinder (sounds like War of the Worlds, doesn’t it?) and see about the clearance between it and the radiator and the bonnet but they have one with a 4 inch outlet and is about 3 inches high so that ought to work.