Base gasket/lube

6 replies to this topic
  • mxgene

Posted September 04, 2007 - 05:52 PM


So I ordered a new piston with Cometic gasket kit for my 426. Two questions for y'all (Gray being the encyclopedia brittanica of YZ's:thumbsup: ),
1- The Cometic kit comes with a sheet metal base gasket instead of the stock paper gasket. Which is better?
2- During reassembly, which assembly lube is best for the cam and piston wrist pin?
I have some from Crane Cams but don't know if the chemicals will degrade the clutch plates.


  • grayracer513

Posted September 04, 2007 - 06:13 PM


I've never seen a sheet metal base gasket. You sure that isn't the head gasket? Or do you have a thin metal shim with a gasket stuck on both sides?

Any assembly lube is OK, but just don't get crried away with it. Apply a thin coat on the cam lobes, and pre oil everything else with you favorite engine oil.

  • mxgene

Posted September 04, 2007 - 06:43 PM


I'm sure. The head gasket, is a sheet metal assembly with three layers held together with a brass rivet on each side.
The tensioner gasket, has the fiber on both sides but not the base gasket.
I am sure it is the base gasket since it has an opening for the O-ring at the case under the cylinder.

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  • Fastest1

Posted September 06, 2007 - 09:14 PM


A metal base gasket from your Cometic kit? I just installed mine tonight and it was fiber! The head gasket was/is a 3 piece metal gasket.

  • 642MX

Posted September 07, 2007 - 04:34 AM


The only base gasket that I've seen that has metal in it was from a CRF450. The base gaskets for YZF's should be a fiber material. Double check that you have the right gasket kit.

  • mxgene

Posted September 07, 2007 - 04:54 AM


To say I was nervous about using the sheet metal gasket is an understatement.
Anyway, I called Cometic and talked with one of the tech guys. He informed me that with the EST kits (better I guess), they went away from the fiber gasket and went to the sheet metal for better sealing.

Just an FYI. I'll upload a picture so everybody can see it.

  • Fastest1

Posted September 07, 2007 - 04:14 PM


So I got NOS? Damn! Thank god it is only a base gasket difference!

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