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XR250r cam journal fixes?


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Has anyone successfully fixed a center cam journal on a xr250r head? This is an 87 I'm working on and the center journal is in poor shape.

I can't imagine the cam flexing enough to wear this out so I'm assuming metal or other debris got between the cam and journal and that's what ate it out.

Can they be bushed? Can you live without it?

I now have two heads with the same issue. 👍

thanks

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Yeah that's a common problem for these motors.

I'm currently rebuilding an '84 with the same problem. I finally just found a good head on ebay for $300.

I'd be interested in how to repair this as well. Maybe bore the journal out for a 2-piece bearing?

EDIT: fyi https://thumpertalk.com/forum/showthread.php?t=346698

Edited by bgibson
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The theoretical reason for the center journal to become galled was explained to me several years ago by a guy who had vast experience with XR engines. His explanation was that the cylinder head actuall deforms slightly under high heat conditions ( the air cooled heads get pretty darned hot) and expand just enough to cause the journal to contact the camshaft. I have worked on quite a few XR engines that had the journal galled slightly. I use fine emery cloth to smooth out the galled area and let it go at that, haven't had a problem resulting from this.

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I'd like to be able to say that mine is "slightly galled", but its more worn down then galled.

I can only imagine this one either got real hot due to lack of oil or otherwise.

The only other thing I can think of is a lack of maintenance, dirty oil and debris caused the erosion of the metal on both cam and journal. I don't understand why people don't do maintenance......

OK, Now I'm wondering how hard it would be to turn the cam down enough to use a 2 piece bronze bushing around it.

I didn't see on XRs only sight where they offer services. May need to call them.

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Yeah that's a common problem for these motors.

I'm currently rebuilding an '84 with the same problem. I finally just found a good head on ebay for $300.

I'd be interested in how to repair this as well. Maybe bore the journal out for a 2-piece bearing?

EDIT: fyi https://thumpertalk.com/forum/showthread.php?t=346698

The 84 & 85 models were notorious for this problem due to poor oil circulation, hot running engine and people running crap for oil. Run ONLY a 100% synthetic MOTORCYCLE racing oil. It can stand the heat much better.

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Has anyone successfully fixed a center cam journal on a xr250r head? This is an 87 I'm working on and the center journal is in poor shape.

I can't imagine the cam flexing enough to wear this out so I'm assuming metal or other debris got between the cam and journal and that's what ate it out.

Can they be bushed? Can you live without it?

I now have two heads with the same issue. 👍

thanks

The 1986 up models didn't have nearly as much problem with heat and galling as the 1984-85 models but excessive heat with automotive oil is just asking for a ruined engine. I have seen many XR250s ruined by running automotive oil like Castrol GTX instead of Castrol motorcycle oil or any other top brand of SYNTHETIC MOTORCYCLE RACING OIL.

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hi guys i have an 84 XR250RE and i have just done alot of work 2 it and i have noticed that mine does not have a centre cam journal at all but i do have to admit that these engines do run hot! but it had fully synthetic oil in it and it still over heated!!!

i am now running motul 3000 4T 20-50w mineral oil still havent got it going yet after wating 6 months 4 the parts but owell!!

regards

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