Bevel box breather..

[weevee]

Can anyone advise whether or not a bevel box breather is really necessary?  My bike doesn't have one, and so far as I know it hasn't yet blown any seals or leaked any oil (..in 18,000mls).  Why do so many owners fit them?

Steve

[Rusnak_322]

if it isn't leaking oil from building up pressure, then I don't see why you would need one.
the previous owner of my bike modified the filler to attach a 3 foot long hose that he had routed under the tank. I tossed that and added a cheap dirt bike gas tank cap vent. never seen any hint of oil around it. Sorry I dont have a better picture.

[John A]

While the filler plug is a handy place to put a breather, it's in the wrong place.  If I remember correctly the crownwheel throws the oil at that area and throws it up the breather so that's why a long hose is used. I've quit useing a breather and now I burp it by opening the fill plug when it's hot, seems to work but maybe it futile.