hello,
my crankcase breather filter has a rubber blue hose from it, to the one way valve, then to the top of the inlet manifold.

been looking on ebay for a black hose, I'm unsure what size if needs to be, as i don't have the original. theres various sizes like 2mm, 3.5mm etc

im unsure whether is the overall diameter or the hold inside the rubber.

maybe bigger is better to get more gas out!!

can someone help

many thanks