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2004 CRF 250x won't start

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My riding buddies 2004 250x won't start after a little problem he had on Monday. Here is a little background. He bought the bike 4 months or so ago. Looked to be well maintained and cared for. It was running perfectly (we have done 3 or 4 rides totalling 150 miles) until Monday. He shifted from second to third and revved the engine to 9-10k, all of the sudden noise from top end and loss of power. He shut it down almost immediately. He then restarted bike and rode it to the trailer to haul it in (running poorly he wasn't far at all). Took it apart yesterday, with engine at TDC cam timing was off 3 teeth! He removed the cam,pressurized cylinder to check for bent valve(no) ,retimed, reinstalled. Bike wouldn't start (popped a few times). Cam came back out removed buckets on intakes to check for missing shims(still there). Exhaust shims still in it too. Pulled left crankcase cover found a valve shim and 3 small metal case pieces. Double checked to make sure all shims are in place(they were). One piece of the aluminum case had an imprint of a sprocket tooth on one side and chain marks on the other. Case pieces were a little webbing behind flywheel where chain comes out of guide. Theory is: the shim was in the head or case already, got into the chain , broke the webbing ,a piece of which got lodged between chain and crankshaft gear(throwing timing off). If it bent a valve it wouldn't have run back to the trailer. My question is :Why wouldn't it start after it was put back in time? Could the cam gear have rotated on the camshaft? Could it have partially sheared the flywheel key(I don't have the correct puller but a screwdriver riding the piston top and tdc mark on flywheel agree). It is firing,has fuel in it BTW. Sorry for the novel, trying to be detailed.

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I would double check timing and make sure there is tension on the cam chain. My '09 450x won't start if it's off one tooth in the right direction; even the dealer messed that up.

Jim.

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Thanks Jim. It is in time according to the marks on the flywheel and the cam gear(and exhaust lobes are pointing to rear of bike). The tensioner does have tension. I will triple check tomorrow just to be sure. We also used his snake camera to look at piston and cylinder through spark plug hole(he is a mechanic by trade,imports). No evidence of piston/valve crash or cylinder scuffing.

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You probably already know this, but make sure you view the cam timing marks by looking straight from the side. Easy to be off a tooth if you just bend over and get some parallax distortion.

I would also check with the cover off that the cam turns as it should. May be something wrong with the bottom gear for the cam chain, but if it's still in time after you trying to start it, I would think not.

Jim.

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I just got my head and cam back from Fast Heads. I am in the process of putting it together and after reading this perfectly timed topic am asking what is the best method, starting from scratch to mount my cam correctly to the right section of the timing chain? My references are as I understand the marked gear on the lower right of the case being in line with the mark on the case and the two hash markes on the side of the cam. But how do I know that it is exactly TDC? I could be 180 dreegs off no?Should I put a screw driver in the plug hole turn the engine and watch the screwdriver to see where TDC is and then line up the cam hash marke to the top of the head? I am a first timer with this type of maintenance.

Guidance would be greatly appreciated.

Thanks

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Shouldn't matter if it is 180 out as the bike fires on compression and exhaust stroke. i use the flywheel timing mark for TDC instead of the gear on right side because it is more accurate. (ignition timing mark is ahead of tdc mark on flywheel)

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Papawhiskey is absolutely right. this is what I was try t post this morning...I guess I forgot to hit the post button.

Only time it matters which way the cam is pointing is when cheking the valve clearance.

180 out does not matter on these bikes for timing, they fire every time the piston hits TDC, referred to as a

'wasted spark" system. As long as all the refence marks are lined up and the piston is at TDC. I had trouble getting my bike to start after reinstalling everything from my valve job. Uninstalled evrything, recalculated the shims reinstalled about a dozen times. I was about ready to load it up and take it to the shop when I thought of verifying TDC with the method you mentioned, except I used a long 1/4 extension ( you should be really careful using this method not to allow anything to bind up). AFter that the bike fired right up.

In the thread I stRTED a while back about this the most recommended method was to use the marks on the flywheel as PW suggested.

Edited by Jakeblues
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Putting it back together with oil tomorrow, hoping for the best,but expecting the worst(had to order left case gasket)! No visible damage to pickup coil or stator. If it doesn't start , what do I do next? C.D.I.? Bump! Will post results once I know.

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Put it back together today and it ran perfectly as always. Still don't know what caused it not to start after retiming. Possibly a very small piece of metal clinging to pickup coil?, but no other ideas on my end. Thanks again Jim Dettman for your input

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Remove the plugs on both cases with allen wrench. Use a allen wrench socket to turn engine through (easier w/spark plug removed and a helper). Align second mark on flywheel with the mark on left case cover(first mark is ignition timing when fly wheel is rotating counterclockwise). Do not back up to the mark if you overshoot! All slack must be taken up front side of the timing chain. Align cam gear marks with top of head,install chain, release tensioner. DANG Jake! I just wasted my time pecking this out! I'm posting it anyway! After you release the tensioner it is a good idea to turn the engine through a couple of times by hand, and recheck timing before it goes back together. Good luck!

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Just proves most of what I know about the specifics of this bike I learned here on TT. I remember seeing something but still have to use the search to find the thread again.

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