Stuff I've Found
The clutch basket was inside of a an eleven hundred motor that still had on its right cover. The friction and steel plates were bonded into one mass that was persuaded to part with a mixture of ATF and acetone at 50:50 and much rapping with a wooden mallet. The valve train parts suggest that very few of them actually go through a hardening process. Rockers worn to concavity; divoted valve stem tips; cams worn down to the base circle. . . I threw out bent valves and flat adjusters before I thought of photographing them, sorry. The cams with the worst lobes still had good bearing journals, so they've been welded up and re-ground to performance cams. The lobe material is now very hard nickel-steel alloy tens of thousandths of an inch thick.
Rocker shafts have very hard surfaces. You can clamp down on them with vice grips as tight as you please without marring the surface. I expect that they are hard all the way through. However, very hard materials tend not to wear well against rotation, especially the back-and-forth scrubbing of the cast iron rockers. Yamaha put a sintered (sp?) bronze bush in the cam chain drive. It is lubricated only by splash and is under tremendous pressure. I've never noted any wear on it at all. If it worked down below, why not up top?