Valve cover bolt leaking

[Brian P]

Also can some one explain to me
how the main gasket might have to be replaced (as stated in one of the above
posts),a s the only comes out around the bolts. Nothing is coming from the main
gasket.

It is not the main gasket that we are talking about. It is the gasket underneath that bolt head.

The bolt is actually a shoulder bolt with a long unthreaded section that projects through the valve cover and through a round gasket underneath the head of the shoulder bolt.

On the photo, look at the bolt closest to the camera - which is not leaking. See the black piece sitting against the valve cover, underneath the bolt head? That's the gasket.

Here's a diagram ... http://www.ronayers.com/CYLINDER-HEAD-C460817.aspx look at parts 15 (shoulder bolt), 16 (washer), and 17 ("rubber mount" a.k.a. gasket). As you can also see, this is a $3 part.

 

[frekeyguy]

It's a tapered (step down) rubber washer.

If the bolt holding the washer in place isn't righted down - then it might leak. But people usually reef on it and strip the threads in the aluminum cam holders.

Actually some bikes it isn't. Re-did a 05/06 636's valve cover gasket...they use a rubber / metal backed cap for those.