Exhaust Header Weird Gasket
 

I have a weird gasket on my exhaust gasket, its not the copper rings but more of a flange that sits inside the header and spreads out to the head.

I'll pop i picture up when I find it, the issue is that the flange bit has rusted through in places and it sounds like it's knocking/tapping/pinking.

Problem is I can't find new flangey bits.

That doesnt sound like a U.S. 91-94 CBR F2 to me. But since you posted in the F2 section I assume you have an F2. It does sound like to 87-90 Hurricane (F1), maybe. I dont remember exactly even though I had first generation Hurricane.

Can you find the part on a microfiche?

I just looked on RonAyers and didnt see nothing that I already knew wasnt there.

The attachments show what I've got. Weird huh!

I'm in the UK, its a UK bike, but all the exhausts I've seen over here are the ones with the copper rings as gaskets.

I though i'd solve the issue by getting a new header, the new one is narrower and doesn't fit to the rest of my exhaust! I think the previous owner put something weird on. I just don't know where from or have any of his contact details.

Dragging this up again as the weather is getting more appealing.

Is it some kind of race gasket?

Could it be a header reducer?

Reducing the ID size of the header could make sense as the gas laws states that pressure and velocity are inversely proportional. This would seem to help with scavenging.

Just a WAG

This is what one looks like. I don't know what it is to be able to search from some new ones.

Attachment 26424

Any pointers are gratefully received.

I have those on my Harley. It's a venturi sleeve that creates a vacuum to suck out the exhaust gasses a little faster. I think they were called torque sleeves, but don't quote me as its been a long time since I got mine. they're not stock, but nice that you have some. If they're not damaged, clean them up and reuse them. Otherwise, leave them out.
Edit:

Found them in my harley book

Attachment 26422

I'm not sure if the Harley ports are the same size as yours or not, but they may be.