78 GL1000 Exhaust

[redsrback6]

I am restoring a 78 GL1000. The PO had after-market mufflers on it, but it has the original headers and shields. I bought original mufflers in very good shape from a guy off ebay, and I've purchased new Honda gaskets 18392-MG7-750 from Partzilla, the seals between muffler-header and muffler-muffler connections. Found a Youtube and it appears the guy puts both headers on first, then the left muffler, fits the crossover piece to that, then he loosens the right header a bit to fit the right muffler on. When sliding the left muffler onto the header, I'm 1/4 - 3/8 inch too long before the passenger peg bolt will fit. I have the gasket tapped into the left muffler as far as it will go, butting up next to the inside ring. The length I'm off by is about the same length of excess overhang of the gasket, which also butts up against the outside ring/nub of header. Is it possible that these gaskets may need trimmed to fit? Any help is greatly appreciated!

[redsrback6]

Okay, took the time to measure everything more carefully and have decided that my left muffler with seal is approximately 1 inch too long to fit my header. Just found a post on theGLforum from a guy a few years ago looking for OEM headers for his '79 to replace SS aftermarket headers which were 1 - 2 inches too long to fit new-to-him OEM mufflers. I assumed my headers were OEM but evidently are not.

[redsrback6]

Took my header to a local motorcycle salvage shop and the guy confirmed my headers are original, so I have OEM headers, mufflers, and the recommended Honda seals. So unfortunately, I'm back where I was. I also spent some time looking at a couple of good views from eBay people selling their GL1000 78-79 exhausts. I do better understand how the clamp works now. There are notches at the tip of muffler to keep the clamp in place on the muffler side. The teeth of the clamp then appears to lock in place over the outer ridge of the header, which tells me the outer ridge of the header butts up against the inside wall of the muffler. This setup would work and fit for me if I didn't need the seals. The problem is the seal is almost an inch wide, approx. 13/16.

A. If designed to sit inside the muffler outer wall butting up against the muffler inner wall, and overtop the header, it will also butt up against the outer ridge of the header making it too long as mentioned. If the seal is suppose to slide over the header ridge like the outer muffler wall then perhaps length wouldn't be an issue but I don't see how the teeth of the clamp would be able to lock onto the header ridge properly. Also, all the eBay pictures I see there is no sign of a seal anywhere.

B. For a few moments I noticed the width of the seal and the clamp were close. So then I thought just maybe the seal is designed to mount directly under the clamp band, overtop of the muffler outer wall... so it won't interfere with the length. A good thought but the seal just seems to narrow to fit over that, especially given that outer wall should expand over the header ridge.

So I'm still searching for an answer. Hopefully someone with recent exhaust experience with 78 or 79 GL1000 can describe how the seal mounts. Grateful to anyone with a thought. I've not really looked at the earlier models.

[redsrback6]

Turns out, these mufflers still had the original gaskets in them, to me just looked like part of the muffler inner wall. This is why I was too long. Unfortunately I'm not finding any easy solutions to removing the old gaskets so I may just stick with the old...

[Winger1957]

Someone can benefit from my input on this topic. I bought a badly abused '78 GL (blue one in the photo) and spent the three winter months of Nov. '20 through Feb. '21 restoring it. That was the most rewarding motorcycle experience of my life. As for the exhaust pipes, I had to throw the generic and rust-gutted 3rd party units away and find replacements, finally settling on two HD Sportster tubes, the long one, so I had two identical tubes off two Sportsters. Installation took about five minutes. There is a bypass port on each tube which you need to plug with freeze plugs. Dorman 555-023-B is probably the correct size and O'Reilly had a box full of them. You need two, and they were about 25 cents each. Nice.

Put the freeze plug into the bypass port whichever way you want to, and seal it in with JB-Weld. Let it dry 24 hours before starting the engine. Perfect fit and good solution. The bypass ports are beneficial if you can connect them, but since you have two identical mufflers they don't line up properly when mounted and etc.

The mounting brackets for the other end of the tubes are your GL factory original units. Just loosen each one a bit so that it rotates, and rotate them so that one of the muffler-mounting holes lines up with the Sportster mufflers threaded female mount point. You will only use one of the holes on each GL bracket. Put the right sized screw through the hole (use a lockwasher too) and thread it into your muffler, tighten it up and you are finished.

They sound very good - not loud, not silent. Good balance and they look native to the bike. Mine cost $90 off ebay and looked new.

[landisr]

Winger1957: What photo?

[Winger1957]

The blue GL on the right, the muffler can be seen in that photo. I can send close ups if anyone wants to see. The sportster mufflers are perfect for gen 1 GLS, and maybe for gen2, also. Cheap, beautiful, high-quality, look good, sound good and available immediately.

[landisr]

I'm sorry, but I don't see any photos here. Is it/are they in another topic or thread?

[Rambozo]

I think he means his avatar photo.
If you are not seeing them, you might have that disabled in your settings.

[landisr]

Oh geez. Thanks. They look good.

Don't get old.... They don't call me Old Fart for no reason.

[GL650GL1000GL1100]

Hello
I am new here first post !
Was wondering if you had any more info on those sportster exhausts you used ? I might go that route on my next 79 restoration
Since sportsters have been made since the sixties and there is 883 / 1200 and so many different sportster exhausts
Thanks