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bjesse60

2002 YZ426 Oil Blow-By?

7 posts in this topic

My YZ426 seems to be putting some oil out the breather tube that comes from the valve cover and runs down the left side of frame, the bike has tons of power and haven't seen the first sign of any smoke out the tail pipe is this normal? Why would it blow out there?

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You over filled the oil.

I hope you are right, is there any other condition that could cause this? The bike runs perfect. I hope it didn't hurt anything?

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... is there any other condition that could cause this?

Yes. Normal operation. There is nothing unusual in a YZF blowing a few drops of oil through the breather, especially ridden hard and/or in hot weather.

If it's really excessive, the rings could be bad, or you could have over filled the engine.

Never check the oil level without first running the engine for a full minute to move the oil back to the frame from the crankcase.

Remember to drain both the frame AND the crankcase when draining oil. Add 1.5 qts, run for a minute, then check and adjust oil level.

http://www.thumpertalk.com/forum/showthread.php?p=5221903#post5221903

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Yes. Normal operation. There is nothing unusual in a YZF blowing a few drops of oil through the breather, especially ridden hard and/or in hot weather.

If it's really excessive, the rings could be bad, or you could have over filled the engine.

Never check the oil level without first running the engine for a full minute to move the oil back to the frame from the crankcase.

Remember to drain both the frame AND the crankcase when draining oil. Add 1.5 qts, run for a minute, then check and adjust oil level.

http://www.thumpertalk.com/forum/showthread.php?p=5221903#post5221903

Thank you, I feel it is just a case of overfill but if the rings were bad enough to cause this wouldn't I be able to notice it through the exhaust as well?

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... if the rings were bad enough to cause this wouldn't I be able to notice it through the exhaust as well?
Not necessarily. Excessive combustion blow by results from bad compression rings. That may or may not have an effect on the oil ring.

The first thing you have to do is get the oil level right, then determine if you're pushing an abnormal amount out the breather.

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Not necessarily. Excessive combustion blow by results from bad compression rings. That may or may not have an effect on the oil ring.

The first thing you have to do is get the oil level right, then determine if you're pushing an abnormal amount out the breather.

Thank you, I just changed the oil today and will take a spin tomorrow and see how it does!

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