oil residue coming out of breather tube?

[800screws]

after riding, i get some oil dripping out of the breather tube on a 02 yz426. is this normal? i just had the top end rebuilt and valves adjusted? something i should be looking for?

[642MX]

They drool when they get ran hard. I wouldn't worry. It also can be caused by over-filling it with oil.

[800screws]

that's probably why then, it's in a hybrid race quad....

[TX-SANDMAN]

My almost new 450 does it as well. Looks bad but I think they all do it some.

[FFRacing79]

Like others have said, this is pretty much normal with the YZF, though overfilling this motor with oil has little to do with it.

There is no baffle in the cam cover like the CRF, but there is a pretty simple fix that will eliminate most of the problem.

When you remove the cam cover, you will notice a "tower" in the head and cam cover just below the breather. You can fill this tower with a low density foam, like they use in fuel tanks or even the outer layer from a 2 stage aircleaner. Put one piece in the head and one in the cover, making sure not to compress it too much but still fit snug. This will act as a baffle trapping much of the oil. Rotax has done this on their case breather motors for years. JMO Tdub