Exhaust sealing question

[Lipdog]

I removed the exhaust on my Chief earlier this week to gain more access to adjust my valves for the first time (went well). During normal use, I tend to get carbon on the outside of the rear cylinder header where it meets the engine. What do folks do to seal these types of joints? I've used Walker Acousti Seal on cars in the past, but never in such a hot application as it would be here, directly where the header inserts into the engine, so I'm reluctant to use it here.
Any tips would be great. Thanks!

https://www.amazon.com/Walker-35959-.../dp/B000CQDL94

[Skirted]

I use Permatex Ultra Copper or Permatex High Temp Red

[tfburke3]

If the pipe fits loose you may be able to get a muffler expander and increase the o.d. a little.
Tom

[ChiefTwoKicks]

Some people use Hi-Temp RTV silicone, its red in color. I don't like it, its messy and hard to remove, later when the need arrises. I have used a standard "metal muffler tape", available at most auto parts. A couple of wraps around the pipe and stuff it in the socket. Then trim the exposed edges best you can with a razor knife. Pretty much depends how much out of round the exhaust socket is. Its not always perfect, but for me it works well.
I got tired of fussing over the sooty black all over the chrome, finally went with black heat-paint on the pipes, with modified HD exhaust heat shields covering the pipes. The shields also prevent your boots from leaving marks and burnt rubber/leather on the pipes, especially near the brake pedal and the inside heel of the right boot.
I modify the shields, cutting and grinding to shape. One clamp strap is sufficient to hold the shield in place, so you can cut and trim accordingly. Here's an example on my rigid frame model, look closely...'36 Blue Chief, c.15.jpg

C2K

[pisten-bully]

I too would avoid any sealers, because as you’ve seen the exhaust needs to come off for valve adjustments, but also for chain guard removal and some other tasks. I used a loaner tail pipe expander from Advance Auto or Autozone and got a tight fit, but the tape idea sounds good, too (better than sealant IMO)

[tomfiii]

The sealant (hi-temp copper) needs to set up, but you can wipe off at edge of spigot before it sets. An expander works well, but work slowly and test fit.

[Lipdog]

Update: I decided against the Acousti Seal exhaust sealant because it’s meant for lower temp applications and not directly on the engine. I was worried it would harden and crack. Instead, I used just a very thin layer of copper RTV inside the rear exhaust port. It’s good to 700 degrees so it shouldn’t harden and I think I can peel it off later if necessary. You can’t see it at all and it sealed things perfectly during my 50mi ride this morning.

[Skirted]

Update: I decided against the Acousti Seal exhaust sealant because it’s meant for lower temp applications and not directly on the engine. I was worried it would harden and crack. Instead, I used just a very thin layer of copper RTV inside the rear exhaust port. It’s good to 700 degrees so it shouldn’t harden and I think I can peel it off later if necessary. You can’t see it at all and it sealed things perfectly during my 50mi ride this morning.

It takes very little gap for exhaust to leak and cause soot marks. A thin film of RTV easily seals up these small imperfections and I've had no issue at all removing the pipe. The old stuff cleans up quickly with the pipe out.

[Sargehere]

An old-time bike builder told me long ago he sealed up exhaust with "'Lasses, just 'lasses!" He was talking about mo-lasses, and he wasn't joking. In years before miracle chemicals, he recounted fitting up the slide-in exhausts like on Flatheads as best as he could, metal-to-metal, disassembling to dip the last quarter or half-inch of the pipe in molasses for a ring on the end before final assembly.
The first time it's fired up the molasses, a hydrocarbon, is turned to a pure carbon ring and seals up the pipe joint. I liked the idea of sealing my pipe joints, but the "natural materials" not so much. He inspired me to simply wrap about a 3/8" strip of muffler bandage about twice around the male end of every pipe that has to be inserted in another, or the head, and I got a well-sealed exhaust. The muffler bandage is invisible and won't deteriorate.