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Question on checking valves...

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Attempted to check the valves on my 04 CRF450R today...

Took off tank and seat

Took off valve cover

Put motor at exactally Top Dead Center w/ cam lobes facing rear of bike

Inserted feeler gauge

and they were CRAZY Tight, like almost no cleareance at all!!! I was checking for clearance as per service manual.

SO MY Q IS...Are the valves supposed to get tighter or looser, because mine are way tight????

Thanks in Advance

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they get tight... time for a reshim and then prolly a valve job....

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as long as there's at least some clearance it maybe not too late for your valves.

just reshim and check again after 10-15 hours, there should be not much of a difference

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I also have an 04 CRF 450 and I just re-shimmed mine for the 2nd time this past weekend. From what the engine tuners are tellin me once the valves move past .50 or 1/2 mm then it's time to have the seats re-cut and new valves installed. Mine have moved .30 mm from the time the bike was new.

You can get the intake seats cut and new valves installed for about $250. There's no need to replace the exhaust valves unless they start to move. Make sure you go to somone reputable like White Bros. Stay away from the small shops. Good Luck!

Todd

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as long as there's at least some clearance it maybe not too late for your valves.

just reshim and check again after 10-15 hours, there should be not much of a difference

yea see thats the thing, there is no clearance, even our thinnest feeler which is .001" (i think) would not fit in any of valves exhaust or intake. Does this mean it needs new valves? Can i install new valves? Or is it best to have a shop install new valves, what does it cost?

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yea see thats the thing, there is no clearance, even our thinnest feeler which is .001" (i think) would not fit in any of valves exhaust or intake. Does this mean it needs new valves? Can i install new valves? Or is it best to have a shop install new valves, what does it cost?

Shops always charge you so much, its best to try and find someone that does that stuff under the table. But before you checked your clearance was the bike running normal? If so and it wasn't hard to start or anything before, maybe you didn't quite find TDC? IDK just a thought... by the sounds of it you may have to reseat your head and replace the valves. :thumbsup:

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You can get the intake seats cut and new valves installed for about $250. There's no need to replace the exhaust valves unless they start to move. Make sure you go to somone reputable like White Bros. Stay away from the small shops. Good Luck!

Todd

Yeah pretty much what Todd said... except you may need the exhaust valves and exhaust seats cut as well.

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Shops always charge you so much, its best to try and find someone that does that stuff under the table. But before you checked your clearance was the bike running normal? If so and it wasn't hard to start or anything before, maybe you didn't quite find TDC? IDK just a thought... by the sounds of it you may have to reseat your head and replace the valves. :applause:

We thought of TDC to and gradually tried many slight variations of TDC, nothing fit! Yes the bike was very hard to start! Usually we resorted to a bump start. Thats a sign right?!? Once it was running it seemed to run pretty strong though. :thumbsup::ride::applause:

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I have never heard of all 4 valve clearances going to zero. Sorry about your luck, but at least you caught it in time. How many hours do you have on it?

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Mine were bottomed out also. If this is your 1st adjustment on the intake you must find out what size shim you have and then subtract .16 from that to determine you shim size. You can find the entire shim listing at www.servicehonda.com in the part finder and there's a shim calculator on www.crfsonly.com.

When the clearance bottoms out to zero you don't really know how far the valve has moved so it's a good idea to buy the next 2 smallest sizes just in case you not in spec on the first try.

I would re-shim the valves and then look keep a check on them every ride to make sure they aren't moving. If the clearance closes up real quick the it's time to have the seats cut and install new valves. If the bike wants to stall after it's hot or gets hard to start stop riding and get new valves.

Todd

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Iv'e NEVER heard of the exhaust valves tightening up like the intakes do!

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It has alot of hours on it, unsure how many but it had alot of time on it when we bought it too. How much does it cost to have the seats cut and the valves replaced?

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We thought of TDC to and gradually tried many slight variations of TDC, nothing fit! Yes the bike was very hard to start! Usually we resorted to a bump start. Thats a sign right?!? Once it was running it seemed to run pretty strong though. :thumbsup::ride::applause:

Yeah thats defiantly the sign. My suggestion is NOT to ride it. I too had to resort to jump starting it and if you ride it like that to long it can cause engine damage (back when I had a crf250). And I wouldn't just re shim it. Most likely it wont solve any thing, it will work the next time or two you go out then it will get hard to start again. Soooo get her to a friends garage that can work on it or bring her to a shop. You will most likely have to have the head sent out to get it reseated.

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When I had the 250 a guy worked on it for me and I had to replace the intakes and have the head reseated. It was like $250 I think? So if what we diagnosed with yours is right then I think it will be atleast twice as much or so.

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Ballpark $450 for intake and exhaust. That's if you take the head off. You might as well put in another piston ($150) while you're at it. Good luck!

Todd

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Ok, thanks guys! I'll have to think about this one for a while.

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yea see thats the thing, there is no clearance, even our thinnest feeler which is .001" (i think) would not fit in any of valves exhaust or intake. Does this mean it needs new valves? Can i install new valves? Or is it best to have a shop install new valves, what does it cost?

Before you take your cylinder head off first perform a valve leak test, that's when you put low air pressure on the combustion chamber through the spark plug hole.

place the camshaft lobes backwards so the valves should be closed (piston in exact TDC or it will move).

When a valve leaks you can very clearly hear air escaping, most often through the inlet valves as in my case.

Maybe you can hear it better with WOT, i don't remember.

When there is no leak i would adjust the valves and run the bike and check clearance again after a few hours.

This is a cost-free test almost everybody can perform at home and when as long as valves don't leak they are as good as new ones. :ride::thumbsup:

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