Excessive wear on rocker arm pawl

I've just started to tear down my 92 XR600 for its first rebuild. So far I've noticed that one of the rocker arm pawls has been worn from convex to concave-there's at least 1/16" of metal gone. This is the pawl for the exhaust valve on the left side of the bike (not the valve with the manual decompressor). The cam lobes measure up okay, with the lobe corresponding to the worn pawl being 1 mil under the service limit. Is there a specific reason for this, or is it just excessive mileage?


Ontario Dual Sport Club

I would check your oil pump and the camshaft for any blockages. That is the lobe farthest away from from the pump. If that all checks out okay then its probably just wear and tear.

I just bought a '93 XR650L with about 10k on it that had the same problem. Bad wear on the same rocker and worn cam on matching lobe. The exhaust seat on the valve was cracked and just about fell out when the valve was removed from the head. I don't know the cause but I see aftermarket cams and rockers that are hard welded. Maybe it's a common problem? I know the previous owner rode it hard and at high rpm. Maybe it was ran low on oil? Maybe it got hot?

I plan on doing a thorough check of the oil pump and all passages before I repair and reassemble the top end.

I just bought a 91 XR 600 with 25000 km´s on it, and have the same problem ...Excessive wear on the left exhaust valve rocker arm ! The pawls are black colored, look´s a


lubrification issue, but i was wondering if it could be a to tight valve adjustment !!!??? Probably not, cause every body who have had this problem is allways on the same valve, the


one that´s far away from the lub point in the head !!!


Low oil level ???


Problems in the oil pump???


Any bodhy have figured this hout ???


I just don´t want to buy a new cam and rocker arms, and in a few rides have the same problem again !


Thank´s for any help




Lisbon, Portugal

Edited by Mig Motorsport

I think if the the valve lash is too tight, the lack of clearance between the cam lobe and rocker pad prevents oil from getting in to lubricate adequately. That would be a possible cause of a single lobe/ pad wearing.

Edited by heart_of_darkness

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