Oil from Breather Tube

My bike (06 YZ450F) left about a half a teaspoon of oil on my bike stand from the breather tube after riding yesterday, is this too much? It has never done it before that I have seen.

You most likely overfilled your oil by that much that last time you changed it. Wont hurt anything.

While you shouldn't be concerned with the small amount left on the stand, you probably left more on the track or trail. What causes the increased vapor? I would imagine that it is air blowing through the valve stem seals. Isn't that the only air flowing through the valve cover aside from expansion due to heating?

My bike (06 YZ450F) left about a half a teaspoon of oil on my bike stand from the breather tube after riding yesterday, is this too much? It has never done it before that I have seen.

I have a little too. Just check your oil often and take note. You should be ok however.

What causes the increased vapor? I would imagine that it is air blowing through the valve stem seals. Isn't that the only air flowing through the valve cover aside from expansion due to heating?
No air or gases in particular will blow through the guides. It's more likely rings allowing combustion gas into the crankcase.

But it may be nothing more this time than an extra hard ride, or a bit too much oil.

What Gray said - besides - your top end is wide open to the bottom end, so there won't ever be any extra pressure developing at the head.

Most will dribble a bit after riding, normal vaporization (misting) of the oil will cause some of it to deposit inside the tube as it breathes positive - if the deposits make it past the highest point, they come down the tube and exit the tube.

What's nice about that is you KNOW you're getting oil delivery to the top end.

Thanks for all the information. I will keep an eye on it to make sure it doesn't become excessive. Bike still runs like new, I have had zero problems with many hours at the track, all hail the mighty 06 :)

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