KX Guru Racing

I imagine this subject has been discussed, but I haven't found a clear answer...in my KX500 engine rebuild, I am using cometic gaskets. Is it neccessary to use any kind of sealant on them? I'm in HVAC for a living, and when I rebuild a centrifugal compressor, all the gaskets are oiled before assembly. In the olden days (back in the 70s), I fancied myself a motorcycle mechanic and used Yamabond on paper gaskets. I'm sure this will be one of those topics with as many opinions as posters , but I really would like a definitive answer, if there is any such thing. Thanks in advance.

You want a definitive answer?

http://www.cometic.com/p-35446-custom-gaskets.html

Aramid Fiber
A premium high temperature, high-density, creep-resistant material that requires no re-torquing and is fuel resistant. All Cometic fiber materials are asbestos free and require no additional sealants.

Aluminum Foamette Material (AFM)
AFM is a chemically blown, compounded nitrile synthetic rubber bonded to an aluminum core with temperature resistance of over 250°F. AFM material has an 85 percent recovery while maintaining strong torque retention. AFM does not require gasket sealers or re-tightening.

All that being said.
There are occasions where I will still use just the slightest skim of Yamabond or similar..
Occasionally I will use it on intake gaskets and base gasket.
On the 2 piece clutch cover gaskets I will occasionally use it depending on how flat they came out after all the welding, grinding, ect.
But for the most part you don't need it.

That's definitive! Thanks Sandblaster!