Rockers come in two flavors, and they are dispersed throughout the series seemingly at random. We pull apart motors and find things like 700s with all hardened rockers and 1100s with none. Some engines have one, two, or three hard rockers. Most have none. The hard rockers are not available from Yamaha: if you order a rocker, 700 to 1100 and the XVS1100, you will get a unit with an unhardened pad where it meets the cam with a largish oil hole dead-center.
Our hard rockers have a layer about 2mm thick of hardened steel. The oil feed is in the arm a little "upstream." Never have I taken apart a head and found these with the least bit of wear. Sometimes I find perfectly convex rocker pads and cam lobes worn down almost to the base circle. How a bike in this condition ran is a mystery.
Anyhow, the typical rocker found has a large central oil passage, and no discernible hardening. These rockers are almost always too worn to run. Some are extremely concave and it gives me pause to wonder how the rider could tolerate the noise. Worn rockers are almost always associated with flattened adjusters and dished valve tips. The adjusters (AKA tappets) should be hemispherical in section where they meet the valve tip. They do appear to have a very thin layer of hardened material. In a pinch, it is possible to wrap the threads against damage and clamp them in a drill. Then carefully apply the edges to a whetstone or knife stele until they are once again convex. At best, this is temporary, as you have almost certainly worn away any hardening. These can typically be acquired new for less than ten dollars a piece. In the future, I hope to be able to offer a kit containing adjusters, jam nuts, and valve keepers -- all in titanium. Not soon.
Holed rockers will work indefinitely if the engine is kept full of fresh oil and the bike is never revved. A cam with over .425" lift or excursions past stock red line will wear the rockers into uselessness in no time. For performance riding, hard rockers must be used. If you study the websites/catalogs of Megacycle and Web Cam, you will find rocker welding services. Typically these run a hundred dollars per rocker - exchange. The finished product looks like these we are offering. You may be lucky and have all hard rockers. Perhaps a couple. Likely none. Performance cams dictate their use.
