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Seized 08 crf450r motor

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My 08 motor which allegedly has 50hrs on it seized. Took the valve cover off and the oil smells terrible and stinks though it's only 1 hr since my last oil change. Additionally I can't see any oil in my sight window. It looks like the left intake valve shim is missing (see pic). Any ideas what went wrong? I had just checked the valves when I did my oil change and they were within tolerance. The 

IMG_0369.JPG

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when you say seized - you mean the piston has no movement ?

what do you mean by allegedly ? did you just buy it ?

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If you say that the shim was there at some point but is now missing what most probably happened is the valve retainer failed the valve fell into the piston and the piston seized.

Possible reason could be that whoever installed the valve did not tap the stem as per the instructions and the keepers did not sit properly.

But you will never know until you take it apart.

Oh and you have to find the retainer the keepers and the sim. If they are not there you have to dig for them inside the engine.

 

 

Edited by jnk
typo

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5 hours ago, jnk said:

If you say that the shim was there at some point but is now missing what most probably happened is the valve retainer failed the valve fell into the piston and the piston seized.

Possible reason could be that whoever installed the valve did not tap the stem as per the instructions and the keepers did not sit properly.

But you will never know until you take it apart.

Oh and you have to find the retainer the keepers and the sim. If they are not there you have to dig for them inside the engine.

 

 

3
4

If the keepers fell out the valve would be down in the cylinder against the piston, But its not the valve is in its normal position!

Edited by ThrustWasher

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Maybe the shim fell down and got wedged in the cam chain somehow between the cam chain and the crankshaft, Which is causing it to be seized! Either way you need to disgnose the issue!

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11 hours ago, S.O.A.N.Z said:

when you say seized - you mean the piston has no movement ?

what do you mean by allegedly ? did you just buy it ?

I bought the bike last yr with 35 hrs on the chassis "allegedly". Seems like it was too good to be true but the bike was pristine and the seller had a lot of money and other toys. Who knows for sure though. The rear wheel locked up on me mid air on an 80' table. Now the kickstart won't turn over and I can see the cam chain is under a lot of tension. Weird thing is the bike wasn't smoking or puking oil but there is hardly any oil left and what is left is black and smells burnt. 

Edited by digarcia1987
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have you at least pulled the filter yet to see if it was producing any metal?

 

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Did you check the oil in both sides to see if some migrated over? 

But yeah you're gonna need to dig into it and see what happened. Head needs to come off at a minimum but I'd just tear it all down, worth the cost of a gasket set to see the whole picture

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First thing Id do is pull the stator cover and flywheel to see what's going on back there. What could have happened, and this is pure speculation....

 

The right side crank seal fails, it pumps all the engine oil into the trans, you keep riding, it get so hot it seized an exhaust valve. Piston bumps it....kicks the shim out to fall into the cam tower...blah blah blah...hatefulness, misery, woe...

 

 

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On 6/18/2017 at 5:41 PM, Shawn_Mc said:

First thing Id do is pull the stator cover and flywheel to see what's going on back there. What could have happened, and this is pure speculation....

 

The right side crank seal fails, it pumps all the engine oil into the trans, you keep riding, it get so hot it seized an exhaust valve. Piston bumps it....kicks the shim out to fall into the cam tower...blah blah blah...hatefulness, misery, woe...

 

 

This is what I was thinking too. I ended up buying a brand new fc450 and then dumped $6k into mods (raptor ti pegs, brake and shift levers, neken sfs, cleaned, fmf full ti 4.1, skid plate, hand guards, frame guard, cTokyo mods ecm, noz n10z suspension, graphics, plastics, annodized bling, chain, wheels, oversized brakes...) so I'm flat broke. I'll have enough to rebuild her in a couple weeks and post what I find. 

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Did you ever find out what the problem was?  I have an 06 crf450r that locked up mid air.I pulled the top end and both side covers . The cam chain felt really tight when pulling the head.once the head came off I was messing with the chain and it came free. .....maybe a bad tensioner??? Stretched chain??? And it bound up on the mag?

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29 minutes ago, Bummer418 said:

Did you ever find out what the problem was?  I have an 06 crf450r that locked up mid air.I pulled the top end and both side covers . The cam chain felt really tight when pulling the head.once the head came off I was messing with the chain and it came free. .....maybe a bad tensioner??? Stretched chain??? And it bound up on the mag?

Your problem is probably the cam chain tensioner. Replace the chain and the tensioner (Id put a manual one on). The auto units go bad/fail-reset with an alarming regularity. Any more than 50 hours on one, and Id say you're on borrowed time on the thing.

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