I have the original carb for this bike that I am looking to rebuild and put back on. It currently has a newer Amal monobloc on it that doesn't look too bad, but I would rather run the original if I can. Neither carb has any sort of filter on them. Does anyone know what the original bike would have come with or what the most period correct and protective filter I screw onto the carb? All the pictures I can find online of original bikes don't really seem to show any sort of filter assembly.