Header Gasket for Exhaust? Yz450

I'm installing a new exhaust on my 2009 yz450f. When I took the FMF one off, there wasn't a crush gasket in there. A while back my mechanic gave me 2 header gaskets. A copper ring & a half flat/round gasket with copper chips in it. Im guessing it's aluminum because it's real soft. Which one do I use? The service manual shows a crush gasket, but doesn't say or show exactly what kind to use. ImageUploadedByThumper Talk1434814077.235092.jpg

Edited by Bturner

Copper is oem

Aluminum is aftermarket

OEM seals better

Personally, I wouldn't use either one.  When gaskets made to OEM spec are crushed into place, they overhang into the exhaust stream, creating like a little speed bump in the tract right where the pipe and head meet.


I use a piece of bare solid copper 8 gauge ground wire from the hardware store, cut to length so that the ends butt together when it's rolled into the exhaust port.  Seals great, won't rattle loose, and stays out of the way.

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