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Oil coming out of air box - help

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Hey, I am looking to get some help on a problem I am having with a 2010 crf250r. I have oil leaking out of the air box behind the mud guard. Over the past 4 times I have rode it, oil has leaked out. Not just a few drips, but enough to have to fill it a bit before every time going out. I haven't over oiled my air filter, put too much oil in the bike, or anything wrong. It gets below the dipstick, so I put more oil to where it's supposed to be and I find oil coming out the air box. The bike has a built motor and is revved a lot. Not sure if either one of those would factor in. Any help would be great. Thanks!

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On my 05,

The first time I had lots of oil come out of the air box drain was when I dropped the bike on a big down hill. Bike was basically upside down and allowed oil to come out of the crank case vent into the top of the air box. I started the bike and rode for about 1/2 hour back to my truck. Stopped and about 4 oz of engine oil came out of the air box drain. Topped up the engine oil and still had oil dripping out of the air box drain until I gave it a good clean. Did not have to re-fill engine oil

Second time was getting tranny oil to engine oil migration which caused too much engine oil and forced into air box.

I agree about draining the vent system regularly. Surprising amount will come out.

So if your actually losing engine oil ie your checking the dip stick......

This is just my take on what I would do and I seem to be getting into more than I want to post but..........

So before you start your bike put it on stand. check oil and make sure it's at the top mark of the dip stick.

Pull the seat and air filter and use a flash light to see how much if any oil is in the bottom of the air box. Pull the little cover at the bottom if you need. You will also be able see if there is oil dripping out of the vent tube at the top into the air box at this point. Check to see the vent at the bottom is clean.

You can Start the bike on the stand with out the seat and air filter but be careful of not getting any crap into your carb. When you start and can see Oil immediately coming out of upper the vent tube.......

stop immediately and do not ride it until you can sort this out

Edited by filterx
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