I had a friend tell me he used "Coppercoat" to coat the o-ring and its seating area and never had a problem after that. It was a cb550 race engine and I have since done this to an 836 engine and still no leaks!!
It comes in a small metal can with a brush in the cap. Permatex brand if I remember, right.
NOT silicone with copper added!!!!!!!!
HB
I used the spray copper coat on the head and base gasket before assembly.
