The Great Exhaust Header Conondrum

[Guest]

Dear all,

Nearing the end of my GS850 GN rebuild, and I am trying to fit my old aftermarket exhaust. It a Sebring 4 in 1 with header flanges that differ from the originals.

The flange from the original headers is 19 mm wide. The flange from the aftermarket Sebring exhaust is 22, 5 mm wide and shaped differently.

If I install the after market Sebring exhaust WITHOUT header gaskets, the clamps are flush with the engine block, and keeps the headers tight in place. If I use the header gaskets, they push the headers out of the engine block, leaving a gap between clamps and the engine block.

As I recall, the headers was mounted with gaskets (and I am guessing that the bike wouldnt have run very well if they were not). I don’t recall having a gap between clamp and block, but then again there might have been....

The exhaust gaskets I have bought as a part of a gasket kit are 5 mms wide, so somethings gotta give, if I am to fit my Sebring exhaust with gaskets flush with the engine.

1. Should there be a gap between the engine and the header clamps? If yes.. how wide.
2. Are there slimmer gaskets available, not leaving as big a gap?
3. Do the exhaust gaskets crush and compress?

Any answers or suggested solutions to this mystery would be highly appreciated.

Attached please find a photo of the aftermarket Sebring header flange.IMG_5774.jpg

[Steve]

Flush is not critical, only a leak-free connection.

Here is a comparison between a stock system and the header (of unknown origin) on my bike.





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[Big T]

The exhaust gaskets do crush
Are you sure you removed all of the old ones?
The depth of the exhaust port is a lot more than 5 mm

[Grimly]

Wouldn't be the first GS with two sets of gaskets in there.
My first one had that for endless miles and it was only when I went to replace the rotted-out system I discovered the joys of the PO.

[DKGS850]

Dear all,

It was a good suggestion, but there is currently no gasket in. I am going for one. Definitely not 2 per port

With the aftermarket headers and no gaskets, the clamps are flush. If I put the gaskets in, there will be a gap between the engine and the clamps. Somewhere between 5 mm down to how narrow a crushed gasket is. I just need to a bit more generous with torque. Maybe I should get some longer bolts for the clamps. I am afraid to strip the threads.

Thanks for you imput, Gentlemen.

[Steve]

As I mentioned (and illustrated) in post #2, "flush" is not critical. Using just one gasket is also not critical. In fact, I have two sets in my bike, intentionally. I have not fully investigated why, but when I use just one gasket, I ALWAYS have an exhaust leak. When I install two gaskets, it's quiet. The depth of the exhaust port would probably support three or four gaskets, but that should not ever be necessary.

Just remember to loosen the rear exhaust mount at the muffler when tightening the header bolts.

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