You guys are always so helpful, so I thought I'd pick your brains on this one;) I'm going to have to rebuild my baby, '93 XR 600R, partly because I broke the shift spindle, partly because it needs new rings, and lastly partly because I have worn down the cam lobe on the left exhaust valve. Here's what I'm wondering: I have heard from guys on this site that the cam lobe wear is due to an engineering flaw that limits the amount of oil delivered to the head because the only source of oil to the head is the miniscule oil line that runs up the right backside of the cylinder. This being the furthest spot from the left exhaust lobe, it doesn't get a sufficient amount of oil. What I'm wondering, is if anyone here has experimented or heard of anyone running a separate oil line from that one oil line over the top of the valve cover, or behind it, to provide more oil to that area of the head? I'm trying to cook something up myself, but thought I'd see if anyone here had already tried and failed/succeeded. Open to any suggestions, thanks in advance.