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Head gasket

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I was searching for threads on mufflers on the 83 XL and came across this post.

http://www.thumpertalk.com/forum/showthread.php?t=775602&highlight=xl600+exhaust

I read that you should use the metal gasket for the head or it will put the wrong pressure on the center bearing? :busted: The guy I bought this from had the head off twice and I seem to remember he reused the old gasket or didnt use one at all. He said he stripped some threads and after getting it to stop leaking told me to leave it. I guess he had to dig some rtv out of the head too. Should I pull the head cover and put a new gasket in it Or just leave it?

Im thinking maybe I should but I have it running so well now I hate to have to pull the motor. What do you guys think? And while Im at it has anyone modified an FMF for the 83? Thanks.

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Put a new rocker box cover gasket on it, the tolerances are setup to have that gasket in place.

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hey I always heard that paper valve cover gaskets ar a no no on the xr's and I have done so as I used an oem metal one...

what I dont understand is to me the paper gaskets look and feel thicker than the metal...in other words it would make the cover have more oil gap on the cam journal...particularily the top journal...

I am told though that the lower journal is the more important one...But I dont see how the gasket would affect the lower journal...just the top.

anywhoo

how is this? why is paper a no no?

cheers

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Put a new rocker box cover gasket on it, the tolerances are setup to have that gasket in place.

Is a "rocker box" the same thing as a cylinder head? I'm sure it's just a slang term for cylinder head.

To answer the OP's question, the cylinder head gasket is a precision metal part. It can be reused if it is not kinked or broken. If your bike has this gasket, it's fine If not, it needs to be corrected. The cam's journals will not have the correct clearance without it.

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There seems to be some semantic confusion about the gaskets here....

Head gasket is short for cylinder head gasket and, not surprisingly, goes between the cylinder and cylinder head.

Head cover gasket refers to the gasket that goes between the cylinder head and cylinder head cover.

Both gaskets should be metal like OEM, especially the head cover gasket.

hey I always heard that paper valve cover gaskets ar a no no on the xr's and I have done so as I used an oem metal one...

what I dont understand is to me the paper gaskets look and feel thicker than the metal...in other words it would make the cover have more oil gap on the cam journal...particularily the top journal...

I am told though that the lower journal is the more important one...But I dont see how the gasket would affect the lower journal...just the top.

anywhoo

how is this? why is paper a no no?

cheers

Gasket thickness doesn't affect the lower journal clearance and many cams don't ever touch the top journal. Some early XL600 head covers don't even have a center journal. What what the gasket thickness does affect is pressure and stress across the head cover with respect to the cam end bearings. Those bearings are held by machined saddles. If the bearings are clamped tight before the gasket is fully compressed it will cause the middle of the head cover to flex as all the bolts are tightened.

I will point out that I do not know how tightly the cam end bearings are even held in normal circumstances. Maybe they're not and paper gaskets are just fine. What I do know is that steel gaskets can be used several times, are very unlikely to fail, and there is no question about them being the right part.

If I had a complete spare head, I would grab some Plastiguage and see what kind of room those end bearings have.

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rocker cover=valve cover

thanks ht for the info.

You are right the bearings are the only thing that are supposed to be held in tightly. I have seen some heads on here with scuffed up bearing saddles Im assuming from a loose "clamping" force between the cover and head. Maybe from using paper gaskets=not enough pressure on the bearings?

In any case

Oem is the way to go for sure.

I would be interested in knowing those specs/clearances and how much is the ideal gap for the cam journals for proper oiling.

Anywhoo...

Cheers!

edit: The manual has a specific torque sequence in order to prevent uneven tightening of the valve cover, Im assuming for the reason you have stated above. There is also a very large bolt/s in the middle of the valve cover compared to the smaller 8's on the perimeter...I remembered this when doing the engine twice...The manual was very clear on where to start torquing and how.

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