[MotoJ]

My '99 has developed a bit of an exhaust leake at the header pipe. There's carbon blowby on the cooler ring and around the port.

Tapping in the pipe with a mallet doesn't do the trick anymore. I was going to try a bead of 1800 degree copper-plus header gasket silicone. Any downside to that? Can it dry out and have little crumbles get sucked back into the engine and clog up an oil way?
I also thought about caulking around the pipe with a strip of exhaust wrap, ala caulking ship planking.

What do you guys do for this condition?

[The Garbone]

I use a med pipe expander..  However, as of yesterday I have notice a little soot buildup from a small leak at the joint, but its been pretty good for about 6000 miles.

[DNash]

Have you put a pipe expander to it yet?

EDIT: Cripes, the Garbone is quick on the draw when it comes to pipe expanders.

[MotoJ]

I have not. looks like a trip to Harbor Freight.

has anyone tried the silicone anyway?

[Arizoni]

The High Temperature silicone/copper gasket sealant is only good for temperatures up to 700 degrees F (intermittent).

The metal temperature of your exhaust pipe can easily get up to over 1300 degrees F if you are riding your bike hard.  Localized areas in the cylinder heads exhaust port may heat up to over 700 degrees F. but won't be over 1100 degrees (the melting point of most aluminum alloys  )

As a side comment,  in a gas turbine engine we used silicone O-Rings in an area which ran at a temperature of 600 degrees F in an air environment and although they were rated to 700 degrees F after 100 hours of service they hardened and started turning to dust.

Digging around the web I found a product that looks like it would do the job.
It's called Deacon 8875, a paste sealing compound that is good for temperatures up to 1800 degrees F, stays somewhat flexible and intended for applications like this.  Here's a link.
http://www.deaconindustries.com/high-temperature-sealant.html

Unfortunately, I couldn't find a source for it except the Deacon company (the one boneheaded link that acts like it will sell it doesn't have it and is just a grab to get you to their site).  I didn't try to contact Deacon because it is an industrial product and I would bet they would want to sell it to me in 500 pound lots.
It does look interesting though.

It would be nearly impossible for any sealant at the exhaust port to get back inside your engine.

[MotoJ]

The Copper Plus header gasket I mentioned in the OP is rated for 1800. made by Permatex. It's probably the same thing.

Thanks for the info. I'll check out the Deacon stuff too.

[single]

I used exhaust system sealer on mine,been on there for 2 years.Aoto Zone,Advance,O'Reilly,etc.

[baird4444]

I've been using the Hi-temp rtv sealer for years. The key is to
let it dry for 24 hours!
         - Mike

[mikail gransee]

I got a copper washer from Lowes and put on mine. Works fine last long time.....

[RBHoge]

CMW (aka NField Gear) has some "goop in a tube" sort of stuff that I have used.   It is messy as hell and you better wipe the excess off before it sets or you will be looking at it for a looong time.   ;})

[500KsGerry]

Its messy but I have  used  wood stove door gasket glue. Doesn't like the vibration much is only drawback. Gerry