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shiny black chips in oil

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i found some shiny black chips in my spent motor oil yesterday. the bike is a 2007 yz250f. i change oil and filter every 10-15 riding hours. i ride trails and am not very demanding.

 

here are some properties of the chips;

they are thinner than a razor and are maybe a mm wide

they are attracted to a magnet.

they are brittle

they are shiny on one side and dull on the other

 

 

I was thinking carbon buildup but not sure if that theory flies while being attracted to a magnet.

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A pic would definitely help. Seems like something's grinding

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thanks for replies,

 

took chips to work so no picture yet. 

 

hey Honda_Power can you recommend any follow up tests?

 

why black?

 

i was very surprised to find the chips were attracted by a magnet.

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YZ250F's do not have "cam bearings". Please ignore ANY & ALL posts by Honda_power. He only posts after stuffing his face with pie. His pie-hole runneth over.

 

The chips being attracted by a magnet indicate ferrous metal. This IS a problem and if I were you I would not run the engine any more until you figure out where the metal is coming from. I would start by pulling the valve cover and looking for obvious damage like worn/blue/discolored cam lobes. Valve spring buckets that are damaged. Check the cam sprockets carefully. Then, if you have the tools, check the cam chain sprocket on the end of the crankshaft as several people have posted that these sprockets wear. If these pieces are sticking to a magnet, they are NOT carbon build up.

 

You can pull the screen for the down tube from the oil reservoir in the frame and check it for more metal.

 

I would be pulling the clutch cover, and/or left side engine cover and look for more metal particles. The stator has magnets in it and it will attract & hold loose metal bits inside the engine as well.

 

Sorry to hear about your problem. Was the engine making any weird noises? Has it ever over-heated? Why do you wait so long between oil changes?

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Sounds like you have the dreaded cam chain slap.

Chain is now history and its taking out your small sprocket on the crank.

Oooooommm ...............I see major rebuild in your near future.

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Might as well do the rebuild now instead of doing it when the motor throws a rod out the cases. 4 strokes are pretty much garbage when they grenade.

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Ouch, sounds like i have problems! I'll start this weekend and let you know what i find.

 

Thanks for advice.

 

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here is a pic of the chips. uniform thickness. shiny on one side, dull on the other. magnet picks them up.

20140529_204327.jpg

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