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Engine sound vid... need some help

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Well I recently purchased a 2011 kx250f and wanted to see what everyone thought about how it sounds.  Its my first 250f and It really seems to me that its a bit loud. Im pretty sure its on the stock crank and piston but not 100% sure and not sure on the hours.

http://th_kxenginevid.jpg

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It could be acoustics from the room you are in, but I don't like that sound.  You need to look at valve clearances first to make sure they are in spec, but it sounds like there may be more going on there.  My concern would be the connecting rod.  If it is a used bike, you should inspect that anyway.  Well worth the effort.

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Don't panic, though.  I am far from the master of engine noises.  Still, I do take a conservative approach to the connecting rods in these . . . only because when they go they can be dangerous, not to mention expensive.  You want to check side-to-side to make sure it's in spec, and there should be no play up and down.  There are many others here with better ears than me . . . 

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Thanks for the response. Ive been pretty busy but im going to check valve clearances and pull of the head and I'll report back as soon as I get in there.

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I am going to take a few guesses, mostly dealing with the piston.

sounds a lot like piston slap to me. I have found a few of these motors with the lead ward side of the piston ( exhaust ) skirt slightly damaged and small hairline cracks showing on the inside of the skirt. this part of the piston takes a lot of force. and tends to get damaged. And the piston is allowed to slightly "rock in the cylinder" causing the noise.

the other problem I have seen is the piston wrist pin hole ovals out pretty bad after long use and it causes a gap in the rod/ piston so you hear the smacking sound when the piston changes direction.

Not counting out crank main bearings, If you listen closely the lower end knock is a definite sound , use a long screwdriver, and place it close to the crank side cover and put it next to your ear and listen, of course while idling. If you move the screwdriver up the cylinder and it gets louder then you have a top end noise, piston etc.

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A little update:  After checking the valves, one intake is a .23mm which is really out of spec, all of the others are in spec.  Cylinder seems to have some wear but should be ok after a scotchbrite and soap ( I hope).  Measured the play in the crank and its between .23 and .24mm. I haven't gotten the piston off yet, that will be tmmrw. 

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