I removed the right crankcase cover of my 2002 YZ426 to replace the water pump impeller shaft (impeller would not unscrew). I noticed that along the top inside rim of the cover there was what appeared to be a machined groove, or more of a band of metal that was machined off. I assume this was caused by the clutch. I'm the second owner, and have no idea if the clutch has been replaced and perhaps installed improperly. The machined area looks to be about 4" long x 1" wide. Has anyone ever seen this type of thing? Thanks for your help. I've never tried to attach urls to images, but the urls are as follows: http://tinypic.com/view.php?pic=25gzbiu&s=4 A close-up of the area of damage is at: http://tinypic.com/view.php?pic=34e280z&s=4 The "machined" area is silver, and the normal areas are darker grey.