Forum

[Graham43]

In the past we fitted breathers to our bikes with an open end so why has the Electra X (and others?) have a duck's bill fitted? I assume the duck's bill allows air to escape but not enter but surely all this does is build up a small amount of back pressure (resistance of forcing the rubber lips apart) for what reason? Anyone got any thoughts on this?

[Adrian]

The duck bill is a cheap and cheerful non-return valve, whether moulded into the end of the breather pipe, Redditch style, or stuck in the catch can like the post 2004 Indian Bullet breather set-up. If I understand correctly this is to maintain a REDUCED pressure in the crankcase, which is what should happen if the engine then pumps air (and any blow-by getting past the piston rings) out of the crankcase faster than it can find a way back in.



A.