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One way valve

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I came across something that I've never seen before. I was installing a new piston and rings in a 07 CRF250F. Of course, I dropped one of the retainer clips down through the timing chain cavity. Couldn't get it out with a maginet so I pulled the side cover off to find a flat piece of metal that was a bit beat up sitting inside the case. I noticed that there was an unusal amount of clutch material in the flywheel side. I took a flashlight and could see that the one way valve was wide open. The original piston and cylinder had about 100+ hours on it and the cylinder was really gouged up. The only thing I can think of is that there was an unusal amount of blow by and caused that one way valve to flutter back and forth eventually breaking off. The crankcase vent hose is clear, and it does have a straight tube from the valve cover that is not plugged so there is no pressure build up there.

Any thoughts?

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replace the valve and clean the screen below the flywheel as well.. while ur there i would install a new cam chain, especially with a 100 hr motor... as for clutch material.. there really isnt any direct path for clutch material to build up on the flywheel.. possibly melted plastic from the valve u pointed out? hows the cam chain guides look? magneto? bike ever overheat or run really low on oil? hopefully none of the oil channels are clogged with that crap..

for the hose coming out of the valve cover it is mainly a "settling hose" for condensation and crap to escape.. but having alot of blowby will sometimes fill this hose with oil.. id keep an eye on the one way jet valve after riding it a bit..

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I did the bottom end on this motor about 20 hours ago. The kid didn't have the money to replace the piston and cylinder at the time, so against my better judgement, I put it back together the way it was. I did pushed him to replace the crank bearings, seals and timing chain. I could be wrong about the clutch material because I don't know how long he went without changing the oil in it. The screen was clean and everything looks fine otherwise. I guess some things aren't meant to make sense.

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