Oil came out of valve cover breather hose?

[AKmotorider]

Yesterday I was rippin hardcore for about 2 hours on and off. Rev limiter bangin, all the works. On one of my short breaks, I noticed a medium sized rainbow beneath my bike on the ground (it was dumping rain). Upon close inspection, it became apparent that a small amount of oil had leaked out of the valve cover breather hose and onto the ground. It was a little bubbly and very warm. This has never happened before, and no, this isn't a brand new engine or anything. I haven't made any changes to the bike or its fuel in a while. I rode for a bit longer, and it did not continue to leak out oil after it was parked. I checked the oil window, and it had leaked out enough that it was down to 3/4 full. Why would that happen? Could it have overheated from me riding so hard, or did something mix in?

 

[cleonard]

A little blowing out at high revs and wide open throttle is not unusual on most bikes. However, it is also a symptom of worn rings that are not sealing. As more combustion gases leak past the rings they have no where to go but the out the breather. At some point the velocity out the breather gets high enough that it carries some oil.

I can't imagine that your riding season lasts all that much longer up there. Pistons and rings have a short life in current bikes and even cranks are usually only good for a couple hundred hours. I'd say that you have an off season project.

 

[timoyz]

You'd better make sure you have a big wallet. Speaking from experience, those damn off season projects, can get mighty expensive.

 

[bobkyle2]

Anytime a modern 4stroke does something that is not normal. Check the valve clearances. A little oil out of that is normal, With the rain it could have made it look worse than it actually was.

Do you ever do compression checks? Well you should .... Keep a note of them, And see if they start falling off.