Help, XR tight valve!

[NDRO RDR]

I need some advice. My dad rides a 96 XR 250. In December '97, he put in a 280 kit ( bored out to fit '85 3rd over piston.) When installed, he also put in new valves and valve guide seals, but not the guides itself.

The current problem is that the right intake valve tightens up to the point of making the bike difficult to start. This occurs after only a few hours (about a day's worth of riding.) Our best guess is that the valve guide is worn and it is allowing the valve to move around in the seat and it is wearing the valve out. Our concern is that we may tear it down and not have enough time to get it back together before our club's National DS the first weekend of Oct.

So I guess my question is, are we in danger of doing permanent damage to the head if we let it go on any longer?

Any advice/help is appreciated.

Rob

 

[SFO]

If you are losing valve lash as fast as you say...

Not tearing the head off for inspection is looking for big problems.
Did you use oem valves?
If you pulled it down now you would still have time to sort it out.
Did you do a valve job?
What was the guide/valve stem clearance like upon assembly with new parts?
How do the rockers look?

 

[NDRO RDR]

My dad spoke to an XR mechanic friend of his. He suspected that it is a broken valve spring. This tends to cause the valve to slam closed rather than following the cam profile. Which hammers the valve and seat. We're pulling it apart tonight, so I'll let you know the outcome.

Rob