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08 yz 250f loosing oil

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I have an 08 yz 250f which I just changed the oil and oil filter on Thursday before I went and did a gncc race this weekend. I noticed the breather vent hose on the very top of the cylinder was leaking oil before the oil change and thought I put too much in last time so I thought I would change the oil and know for sure after this race if it did it again. Well it did... I have no clue how much oil I lost which could obviously be very bad for the engine and I can't change the oil every time I ride because an unknown amount was lost. What is causing this and how can I fix it? One of my friends mentioned something about the crankcase being pressurized or something? I have no clue. I am attaching pictures I took once I got home. Notice how there is dirt and mud then right at the bottom by the shifter there is all the black gunky oil where the hose is venting. ImageUploadedByThumper Talk1401109948.635585.jpgImageUploadedByThumper Talk1401109962.361509.jpgImageUploadedByThumper Talk1401109974.391721.jpg

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Some amount of oil mist being expelled is normal.   What I noticed about your hose is it runs straight onto the frame.  Mine is slightly turned down and is outside the frame so the mist does not collect onto the frame.

hose.JPG

Edited by ronbuell

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Some amount of oil mist being expelled is normal. What I noticed about your hose is it runs straight onto the frame. Mine is slightly turned down and is outside the frame so the mist does not collect onto the frame.

I suppose so but I just feel like it is an excessive amount and it just started doing this recently. I have had the bike for a year or so and never done it before. When I cleaned the bike up today there was a lot more there than what I thought originally. And I have to route the hose there, my massive skid plate made for the woods just catches all the oil and keeps it against the frame there

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Then I would ask, How long since last rebuild?

And was the cylinder replaced or replated on last rebuild?

 

The plating does not last forever and it will go out of spec, allowing blow-by, which is what the vent is for, and you are saying its excessive.

Time for a rebuild.

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Plus one on what Ron said. Do a search for blowby on either Google or this site. That way you will understand what we are talking about. The vent hose is for blowby.

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Well I have rode 3 times this week, all pretty hard, and very little if any oil has come out the breather hose at all. I assume I overfilled it before the race last time and or didn't drain all the old oil out. I will def keep an eye on it after every ride and race though to check n see how much i lost. The bike is getting close to having 2 seasons, about 100 hrs, on the original too end so I'm sure by the end of this season that will

Be my winter project

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