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Compresion coming out hole on the right side of the head

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I am working on a 2008 KX250F and it has compression coming out the small hole on the right side of the head. Does anyone have any ideas?:smirk:

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I am by no means a mechanic but that does not sound very good...Maybe compression release or a stuck valve???Hopefully someone with some knowledge in this area can help you...This is something I havent heard of personally but I am curious now to know as well.

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That's a breather hole so water can evaporate from the sparkplug well. If you feel air coming out of there when you kick it, your sparkplug may have come loose.

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Get a new sparkplug with a fresh crush washer and tighten it acc. to instruction.

If compression still is lost out through the hole, there must be a crack and you need a new cylinder head.

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:smirk: I guess ya learn something new everyday...i had no idea there was even such a thing on them.lol lol I feel like a idiot now knowing I have rebuilt these heads before. :smirk:

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I had a suzuki do that to me and the piston skirt was cracked from the bottom coming up to the lower ring and running around towards the wrist pin. You better tear it apart.

CP

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I had a suzuki do that to me and the piston skirt was cracked from the bottom coming up to the lower ring and running around towards the wrist pin. You better tear it apart.

CP

I dont see the connection between a cracked piston skirt and compression getting past the spark plug?

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It is possible that you are not feeling compression coming out of that hole. It could be crankcase pressure created by the back side of the piston. If the crank case vent got blocked it could have caused the rocker cover gasket to blow into the spark plug cavity and let the crankcase pressure escape through the vent hole.

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