KZ400's had these endemic oil leaks, and actually had a recall in the 70's to fix them. Of course nobody actually took their bikes in, so every one I've ever seen still leaks from the same places. The factory repair spec sheet calls for getting rid of the old "o-ring"and use a non-hardening sealant of some sort when reinstalling the valve cover after a rebuild. Is Yamabond okay to use?
