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CRF250X cam upgrade to OEM 250R require valve train replacement?

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JD jet kit

280 athena kit (just purchased today-not installed yet)

powerbomb and Q2

stage one hotcams (currently)

powernow intake insert

top of airbox removed and no backfire screen & pink wire

stock 04' head and valves

Ride style varies between single tracks and fire lanes to power lines in Michigan - looking to complete the overall performance package of the power from bottom to top.

I have a 04' crf250x and would like to upgrade to a new OEM 250R cam, probably an 08' cam from what I have read so far. I could be persuaded to go with a different year for the right reasoning but my question is if I were to drop a 05-08R cam in my X do I need to change anything else in the valve train or can I simply just switch the cams out? 

If this particular info has been discussed somewhere else please let me know. 

Thanks for all the help!

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From what I remember reading & seeing on a dyno chart,

apart from the very lowest rpms (say around 4000 to 5000rpms) the Stage 1 Hot Cam

is actually comparable in midrange torque to the X cam and, comparable in top end HP to an R cam,

meaning it has the benefits of both OEM cams with no 'weak spots' in the powerband.

 

But perhaps a bit more searching is required to confirm if it's the best match for a 280cc engine.

Edited by mlatour

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If you are going to install a OEM R cam I would go with the 08-09 cam.

I dont know if you are using the original cylinder head but the newer cyl heads are an upgrade in a few different ways, including helping with valve longevity and port design which will help with performance and make installing a different cam more effective. You can drop in an OEM cam without concern generally, but if your still using the original old head and valve train components or dont know if all the parts are still original it would be a great idea to at least get new valve springs and seals installed. The valve springs have been upgraded and its a great idea to use the ones called for with the year cam your putting in, along with replacing anything else that may be worn such as cotters, retainers, buckets etc.

Here is a link that may be helpful about 250X related info, dont know how up to date it is.

http://rickramsey.net/CRF250Xbigbore.htm

 

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Assuming all is within spec,  the components that worked with the stock cam can work with the 08 cam.   I have a couple of 2004 crf250 heads,  and you would see more from your crfx in terms of top end with one of those.  That said,  I like the 2008 head with my bike better.  I like staying with cams that are happy with stock spring pressure.  I have a set of Faction springs that seem to do the best at defying my logic there though. 

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37 minutes ago, TDW said:

If you are going to install a OEM R cam I would go with the 08-09 cam.

I dont know if you are using the original cylinder head but the newer cyl heads are an upgrade in a few different ways, including helping with valve longevity and port design which will help with performance and make installing a different cam more effective. You can drop in an OEM cam without concern generally, but if your still using the original old head and valve train components or dont know if all the parts are still original it would be a great idea to at least get new valve springs and seals installed. The valve springs have been upgraded and its a great idea to use the ones called for with the year cam your putting in, along with replacing anything else that may be worn such as cotters, retainers, buckets etc.

Here is a link that may be helpful about 250X related info, dont know how up to date it is.

http://rickramsey.net/CRF250Xbigbore.htm

 

Thanks for the response. I am the original owner of the bike. The head is stock and so is all the valve train, nothing has been replaced. Only shimmed when needed. I do need to re-shim but they are extremely close to spec. I was looking at using the 08' cam but through some post I read people were stating that the valves and springs need to be replaced to accommodate the newer cam.

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35 minutes ago, ossagp said:

Assuming all is within spec,  the components that worked with the stock cam can work with the 08 cam.   I have a couple of 2004 crf250 heads,  and you would see more from your crfx in terms of top end with one of those.  That said,  I like the 2008 head with my bike better.  I like staying with cams that are happy with stock spring pressure.  I have a set of Faction springs that seem to do the best at defying my logic there though. 

I know the valves need to be slightly shimmed but they are very close to spec , I will do a double check once the head is removed. I was thinking about completely upgrading the whole head with port work but that will have to wait for another time. Did you see mostly all top-end performance? Do you have to ride high in the range to feel a noticeable difference or is it something you can really notice starting in the mid-range and throughout.  

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12 minutes ago, OneLung said:

Thanks for the response. I am the original owner of the bike. The head is stock and so is all the valve train, nothing has been replaced. Only shimmed when needed. I do need to re-shim but they are extremely close to spec. I was looking at using the 08' cam but through some post I read people were stating that the valves and springs need to be replaced to accommodate the newer cam.

Its the original head and still has the original valves in it?

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Just now, TDW said:

Its the original head and still has the original valves in it?

correct! 

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Does the bike have many hours on it?

Probably not a lot of those first bikes are still running around not to mention with the original engine components, especially the Intake valves!

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2 minutes ago, TDW said:

Does the bike have many hours on it?

Probably not a lot of those first bikes are still running around not to mention with the original engine components, especially the Intake valves!

I couldn't say exactly but I would say somewhere between 300-350hrs. 

 

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With having the original head and a lot of hours on it like that, I would include the head in being part of the rebuild.

As far as the 08 cam and what to expect after its installed-comparing it to a stage 1, it will be most noticeable or different from mid into the upper rpm range. The stage 1 does a good job in the lower and into the mid rpm ranges and is a noticeable improvement from the stock, original cam. On our 250X which has quite a few modifications at this point including the 08 R cam, several cams have been tried including the stage 1, 05 R cam and the 08 R cam. The stage 1 wasnt a lot different than the 05 R cam but the 08 R cam is the best of that group and gave the engine more power everywhere but most noticeable in the mid to upper rpm range. There was no power loss in the lower rpm range either. It is a noticeable bump up in power but not at all radical.

 

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2 hours ago, OneLung said:

I know the valves need to be slightly shimmed but they are very close to spec , I will do a double check once the head is removed. I was thinking about completely upgrading the whole head with port work but that will have to wait for another time. Did you see mostly all top-end performance? Do you have to ride high in the range to feel a noticeable difference or is it something you can really notice starting in the mid-range and throughout.  

I had never ridden that individual bike as I bought it as a set of forks with the bike thrown in free.   I have some friends who were able to get me a set of crfx crankcases all full of gears and crankshaft so I decided on a build.   Anyway,  I had ridden a couple of 2004 crf's and one 2004 crfx.   The one I built has an RPM ice cube cylinder that they call 280cc's.  It pulls quite nicely everywhere.  The head is a 2008 that was reworked by Fastheads a really long time ago with different seats for the intakes,  and different guides for the exhausts.  I haven't got a whole lot of time on it considering.   One of my friends who has a crfx feels like his is a bit happier idling around,  but my rig ( I have tried three cams,  04, a Web, and an 08).  The web is a grind that is happy with stock springs.  Came to me,  and it is maybe the best all around,  as it is way nicer than the 04 down lower.  Your cam from hot cams is probably as good as any of them.   My next project is to get one from Web Cams that has a sprocket you can change timing on.   (That becomes an addiction.)

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