valve replacement??

mxracer239
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mxracer239
Edited Date/Time 9/16/2015 6:19am
my step son has a 08 crf250 that the valves need replaced, if we go with the stock valves can we install ourselves or do the vavles have to be cut?

thanks
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DPR250R
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DPR250R 9/15/2015 11:37am
9/15/2015 11:37am
mxracer239 wrote:
my step son has a 08 crf250 that the valves need replaced, if we go with the stock valves can we install ourselves or do the...
my step son has a 08 crf250 that the valves need replaced, if we go with the stock valves can we install ourselves or do the vavles have to be cut?

thanks
Depends on the condition of the seats.

I would pull the head, disassemble and check it out. You have a couple options after you inspect head...

- if seats are in good shape, lap SS valves in
- send original head out and have it rebuilt
- buy new stock head and valves
DPR250R
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DPR250R 9/15/2015 11:37am
9/15/2015 11:37am Edited Date/Time 9/16/2015 8:35am
... Oh and personally I would switch to SS valves and ditch the OEM ones...
Paw Paw 271
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Paw Paw 271 9/15/2015 12:14pm
9/15/2015 12:14pm
If you use new OEM valves...The valve seats in the head will have to be recut, but that is also true with most any valve replacement. You can lap stainless valves, but if the seat is bad the all you are doing is making the valve bad as well.
You can't lap OEM valves.

Paw Paw
BobPA
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BobPA 9/15/2015 3:05pm
9/15/2015 3:05pm
Paw Paw 271 wrote:
If you use new OEM valves...The valve seats in the head will have to be recut, but that is also true with most any valve replacement...
If you use new OEM valves...The valve seats in the head will have to be recut, but that is also true with most any valve replacement. You can lap stainless valves, but if the seat is bad the all you are doing is making the valve bad as well.
You can't lap OEM valves.

Paw Paw
This.

A valve seat touch up is cheap BTW...

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jsmx97
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jsmx97 9/16/2015 6:19am
9/16/2015 6:19am Edited Date/Time 9/24/2015 10:46am
The valve seats do not always have to be cut. It does not matter if you use TI or SS valves. What matters is the seat to valve contact area and width. If the seat is pitted, chipped, or hard to decipher the 45 deg sealing angle; you should at least have it inspected by a local shop or engine machine shop.

If the valve seats don't need to be cut, there is no sense in wasting a cut. Generally you can only get away with two separate valve seat re-machining's before the valve stem protrusion measurement becomes too large making it hard to shim the valves.

If the stock seats are in good shape, I would recommend switching to either the Kibblewhite stainless intake valve conversion kit or the Xceldyne X2 stainless intake valve kit.. both good options and both will far outlast stock or any other titanium valve.

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