Valve cover gasket

[srq68]

Reading all the threads about adjusting the valves and changin cam chains, it looks like some of you open and close that valve cover quite often. My question is: do you replace the gasket each time, or do you put joint compound? Everytime I open mine, I have to scrape the old gasket off and install a new one with coumpoud if I don't want any oil traces.

Also, what is the mechanical function, if any, of the half moons at the ends of the head? Why not having a straight edge?

[ratbyk]

Cover Gaskets

What I do is glue the gasket to the cover with weatherstrip adhesive. I usually get 2-3-4 R&R's. I do not put any form of adhesive in the cylinder head side. I do put a little RTV sealant on top of the 1/2 moons. The half moons are glued in again with weatherstrip adhesive. It is super stuff. BUT! when it comes time to remove the gasket liberal use of gasket remover and an exacto knife is used.
The cut out for the 1/2 moon in the cylinder head I believe was to allow the line bore machine or what ever it was that Yamaha used to machine the cam main bearings. The halves in the head and inside the cam caps would have been machined at the same time with the caps torqued in place to provide a perfect circle. Do not ever get these caps mixed up or turned around. Failure is almost guaranteed.
Ken/Sooke