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At my end

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I have an 06 crf250r

I did a full rebuild on it this winter cause it grenaded on me last summer

New crank cases, berrings, seals , crank, rod, piston, cylinder, I reused the valve train cause it was in spec and seemed fine after the rebuild it started right up but it has been a long cold winter here so it sat for about 2 months in storage. When I got it out it was really hard to start but when it did I did a break in changed oil and went out once after still hard to start so I drained gas cleaned and adjusted carb checked valve clearance checked spark it was hard to start still but got it running only to have it die after a couple min of easy riding so I sent the head away all new valves, guides, seats, full new top end gaskets ect get it back together hard first start but runs for about an hour with 2 shut offs in there I get home wash it and put it away only to try to start it the next day with nothing so I pull the carb clean it again put the bike back together starts hard but runs fine go about 6 min down the road and it quits out of the blue no noises nothing out of ordinary I can not get it to start again not even sputter . so I pull the fuel line off to see if its getting fuel it flows fine but a couple drops land on the oil filter cover and boil off instantly. Maybe too hot?

So I push the bike all the way home about 15 min get to my driveway and feel the motor still warm but not hot so I give it a kick it sputters a bit but nothing

Any suggestions

Bought this bike for 3000 rode for a month, motor blew I have now spent 3000 on parts and still cant get it to run right but I can rebuild it with my eyes closed

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You got the cheap berrings. You need bearings! All kidding aside. You should do a leak down test and make sure you rings and valves are sealing. Then I would double checking timing and valve clearances even though you said they are good. After that i would dig into the carb and then electrical. Take some readings any make sure everything is sound.

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So I tore into the bike again tonight pulled the oil filter and found a ton of metal the silver kind so I pulled the stator cover off and found a large flat piece of metal that evidently has taken a trip around the timing gear potentially skipping the timing I didnt have time to check the timing yet the only part that would be the right size and shape as this piece of metal I found is the one way valve between the two case halves so my question now is how could the one way valve tear off has this happened to anyone before? Does anyone have one out of the bike and can measure the metal thickness of the one way valve so I can check if that is what I found? How bad is it to run the bike without one?

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There's another post on the one way valve and yes I found the same thing after a rebuild odd it was stuck to the pickups around the stator , I am still running bike like that as I'm not splitting cases for a 10 dollor part if not mandatory! I am experiencing a little oil consumption between rides and its ending up in the vent tubes and airbox , from what I was told the valve closes on the comp stroke to help keep from pressurizing the crankcase , like I said that's how it was interpreted to me by my mech , he said to check your oil often and deal with it since I've got 65 hours so far on the build and it's been that way from the start as far as I know , you can bet ur ass that when I do rebuilds from now on that will get replaced with new!!!

As far as the thickness I would say maybe 10 to 12 thou not sure just guessing

Edited by Whatwentwrong

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Yeah thanks I got the time to check timing again tonight turns out that one way valve piece rolled over the cam chain gear on the crank and skipped the timing ahead two teeth so once I got that set back to normal the bike fires up no prob if you say its ok to run without that valve ill just leave it for now and just keep an eye on things I already have the part and new gaskets on order so ill have it if need be thanks again

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