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Ashman_46

2009 YZ250F Leaking out of hole in cylinder. Please help

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Hi guys. Today I was riding my 2009 yz250f around some trails and on the beach. After about 1/2 an hour there was a small amount of sticky/tacky yellow liquid leaking out of the small hole in the cylinder. In the attached photo the hole is shown towards the bottom left corner of the photo in the center of the cylinder. I assume it is right where the valves are, what could be leaking out of there? I have searched on the internet but couldn't find anything about it. Has anyone else had this or know of this? Or even just has any info on what this hole actually is? Thanks

yz250f engine.jpg

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I think thats the drain hole for the spark plug tunnel? Its there to allow any water that finds its way into the plug area to drain away. If the rocker cover gasket is leaking in that area, any oil collecting there would drain out too. have a look down the plug hole and see if its oily in there...

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Yes, that is a weep whole for the spark plug tube. The tube is sealed by o-rings. Chances are you have an o-ring leaking. If you pull the valve cover off you will see how it functions.

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That is the spark plug well drain, but the well is sealed only by the plug boot/coil seal on top (which is not your problem) and by the cam cover gasket, which is the likely culprit. No O-rings.

A second, much simpler possible cause, even though less likely, is a loose spark plug.

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Alright thanks guys, Ill check if the spark plug is tight and if there is anything in the tube. Nothing has leaked out since so hopefully isn't a big issue. Might take the rocker cover off if I have to.

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