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chunks of brass in cylinder, where are they from?

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I'm trying to help my neighbor out with this 06 crf250. his son said it made a weird noise then lost compression. I've got the head tore off and there is some pretty bug chunks of what looks like brass in the cylinder. they've only had this bike about 3 weeks and it supposedly only has about 15 hours on a new cylinder, piston and intake valves, not sure why the exhaust valves weren't done at the same time but everything in the head looks ok, cylinder still has the cross hatch marks and no visible damage.

 

so can anyone tell me what these chunks are from? it almost looks like a jet got sucked into the cylinder, is that even possible? haven't checked the carb out yet.

 

0FF4BEAD-6C48-4B02-AB83-0D30F6A3824F_zps

 

263F1550-7482-40C8-B0B3-E8DBE602733A_zps

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Thats strange

 

Its unlikely that brass shavings from the crank bearing could get on top of the piston.

Thats the only place there's brass colored anything in the engine.

 

Its possible a valve seat or guide started to fragment. But they would have to be after market, OEM aren't Brass.

Shine a light down the intake and exhaust ports and see if the guides are intact.

then look at the seats.

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There are no unreliable 4 strokes.

Its the guys working on them that make them unreliable.

And too many Dickheads out there claiming all new parts and rebuilds that are more than happy to pawn their shit boxes off on to some unsuspecting kid

Edited by nesc103y
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Yep. Not many guys will pay to refresh a motor just to turn around and sell it. That should raise the BS Meter to full red...

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There are no unreliable 4 strokes.

Its the guys working on them that make them unreliable.

And too many Dickeahds out there claiming all new parts and rebuilds that are more than happy to pawn their shit boxes off on to some unsuspecting kid

Thats so true maybe the previous owner let a jet fall in the air fiter/air box intake area and its made its way out and into the engine,take a good look at the carb to make sure nothing has fallen out just a shame your the one who has to sort it out now.

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That's a lot of brass. I can't think of anything made of brass on that side of the piston except for some parts in the carb. Did it seize?

 

it is a lot

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It could be the needle inside the carb broke free and found it's way into the cylinder.. Or pieces of a valve guide.. or something that fell into the air box during a filter change.. Or something that was left in the intake tract while the head was off being serviced.  I'm interested to know what it was as well. If/when you figure it out, let us know.

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