Hi everyone-I checked my clearances before doing the MCM mods this weekend and all 4 valves were out of spec (bike has 14,000 miles). So upon inspection of the lifters, I found the L/H exhaust with an unusual circular wear pattern probably about .005" deep-see pic attached. Has anyone ever seen this condition? The cam lobe appears to be fine which I find very strange.

 

To reply, I haven't. That was definitely strange looking. If it was the left side exhaust valve, it might have had something to do with the compression release in some way.

 

Was that valve particularly tight? Not sure on the KLX cams, but some are ground at a slight angle to promote rotation to clear debris and even out wear. I'd see if the marks line up with the lobe edge at that diameter with the valve spring compressed by the lobe.

 

It was the left exhaust valve and it was at .14 mm so not too tight. the wear pattern is about 10mm beyond the edge of the cam lobe. I will replace the bucket (lifter) and I have already completely removed the ACR so if it was related to that like KLX678 suspects, I should be good to go for a while. I don't think I should sand the wear mark out of the existing lifter. Thanks for your opinions.