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Valve Order

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Hi guys,

I just got a CRF450R that has been partly taken apart. The valves have been taken out of the head. My problem is the valves where not numbered so I have no idea which seat the intake or exhaust valve came out of.

Can lets say a exhaust valve be taken out of the right head seat and be installed into the left head seat? If I use new shims and re shim?

Thanks

Mike

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it some what depends on how any hours are on that head. but no dont do it! reason i say about the hours is that when the valves are seated and get there angles they are for that (right or left) seat and that one only. im not saying they wont work for the other seat but they will not last nearly as long and will not perform as well. after time there are microscopic carbon buildup under the valve and the seat. that debris somewhat forms to that valve. now switch that valve to the other side and there will be microscopic gaps. this will cause the valves to not last as long and will cause performance problems. if you dont know which valve is for which seat i would probably just take the head and get a valve job done. while your there get yourself some ss valves.

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Sounds like a great opprotunity for you to send the head out to get the valve seats cut. Then buy new valves and springs to rebuild the head. Go stainless and then you will have a head that you can enjoy and not have to shim all the time.

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if it is a bike just used for pleasure, i wouldn't worry too much. You have a 50/50 shot of getting the valves in where they were before.. well, a 25% chance of getting it totally right if my statistics from college is serving me right. :lol: Valves spin, thus they don't move exactly up n' down like the piston does.

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Hey Guys, Thank you so much for all your responses. The valves don't really even look that bad so I might try the cheap way and just put them back in. The bike is not going to be raced or anything it's just for pleasure riding.

I guess the worse that could happen is they might leak a bit wear out faster.

The funny thing is the last owner did number the valves but he put no corresponding numbers on the head :lol:

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The funny thing is the last owner did number the valves but he put no corresponding numbers on the head

Can you ask him if he had a numbering scheme?

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Actually I did ask him but someone else took it apart not him and I don't think he wanted to find the guy. I did put them in and did a pressure leak test with liquid and did find they sealed better in one way then the other.

A valve job is going to be done in the future for sure but I might ride it a bit as is with new piston crank cylinder and current valves and seats

Thanks Guys

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Hey Guys, Thank you so much for all your responses. The valves don't really even look that bad so I might try the cheap way and just put them back in. The bike is not going to be raced or anything it's just for pleasure riding.

I guess the worse that could happen is they might leak a bit wear out faster.

The funny thing is the last owner did number the valves but he put no corresponding numbers on the head :lol:

go down to the store and buy some valve lapping compound and just lap the valves man ahha. easy cheap insurance. look up a vid on how to it is VERY easy and takes no time and money

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go down to the store and buy some valve lapping compound and just lap the valves man ahha. easy cheap insurance. look up a vid on how to it is VERY easy and takes no time and money

You don't lap titanium valves. That removes the protecting coating and you are left with the unprotected soft titanium.

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Yes the 2004 stock has the titanium intake valves but ya I should be able to due the exhaust valves with no issues. Thanks

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Sorry that I didn't explain more. I was talking about the exhaust mainly as in my other posts. But yes don't lap titanium valves you are absolutely correct. But if you go buy some kw valves and springs and new stem seals you will be golden.

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I wonder can I use the old springs, retainers etc with some new valves? and get the seats re-cut and put it back together

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as cheap as springs are, it woudl be a good idea to get new springs. retainers and keepers i use over unless they show some damage. Again, much depends on how you ride. If your riding higher rpm alot and a faster rider, it is more important to get the new springs. THe MANUAL shows a minimum lenght spec, but that is a crude way to determine if it's sacked out. Lots of hours? just get new springs.

other stuff like cut seats? will get lots of opinions on that from leave it alone, to buy a new head.. have a qualified mechanic take a look at it. again, with enough hours it isn't a bad idea to cut the seats if your putting new valves in.

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