78 GL1000 Exhaust

Discuss everything about Honda GoldWing. Feel free to ask any question related to GoldWing.

Moderators: CYBORG, Oldewing, robin1731, Forum Moderators

Post Reply
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

78 GL1000 Exhaust

#1

Post by 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 not the copper rings. Found a Youtube which shows the guy puts both headers on first, followed by the left muffler, then fits the crossover piece to that, lastly he loosens the right header a bit to fit the right muffler on. When sliding the left muffler onto the header my bike, 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 will butt up against the outside ring/nub of header. Is it possible these gaskets need trimmed to fit? The right gasket doesn't have overhang but the other 3 all do. Any help is greatly appreciated!
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

Re: 78 GL1000 Exhaust

#2

Post by 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.
User avatar
Whiskerfish
President
President
Posts: 36850
Joined: Thu Feb 16, 2006 9:34 pm
My Album: http://www.ngwclub.com/gallery/v/wingmans/whiskerfish/
Location: Norfolk Va

Re: 78 GL1000 Exhaust

#3

Post by Whiskerfish »

OEM headers are split inside. Aftermarket are one hole and single wall.
"Agreement is not a requirement for Respect" CDR Michael Smith USN (Ret) 2017
"The book is wrong, this whole Conclusion is Fallacious" River Tam
2008 GL1800 IIIA "TH3DOG"
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
and a whole garage full of possibilities!!

Psst. oh and by the way CHANGE YOUR BELTS!!!!
User avatar
pidjones
SUPER BIKER!!!!
SUPER BIKER!!!!
Posts: 3237
Joined: Wed May 22, 2013 4:06 pm
Location: East TN

Re: 78 GL1000 Exhaust

#4

Post by pidjones »

I had a similar problem with a beautiful set of SS headers on my '79 that I wanted to mount a set of mufflers that I had from a '78 on. Ended up getting a set of headers from a board member and selling the SS set (hated to - they were gorgeous) everything fit then. Remember that one side cylinders are offset from the other side, too!

Oh, and '77 and earlier headers exit at a different angle.
"Love 'em all.... let God sort 'em out!"
Ex 2006 GL1800 - the Black Pearl SOLD! to make room for:
2021 Can-Am Spyder RT Limited Dark Chalk Metallic
1975 Red GL1000 project - ex Pistol Pete project
1972 Triumph T150V Trident rescue - finished and FOR SALE!
1976 Yamaha RD400c
1978 GL1000 with '75 engine - the Hunley
Ex 1978 GL1000
Ex 1979 GL1000
Ex '79 CB750F rat bike
Ex '86 SEi
Ex '77 GL1000
Ex '76 RD400
Ex '72 Penton 125 set up for flat track
Ex '73 RD250
Ex '68 TR6C - chopped
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

Re: 78 GL1000 Exhaust

#5

Post by redsrback6 »

Very much appreciate the responses from you guys! 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.
User avatar
5speed
Honored Life Member
Honored Life Member
Posts: 5311
Joined: Sat Jul 11, 2015 2:37 pm
Location: Nova Scotia Canada

Re: 78 GL1000 Exhaust

#6

Post by 5speed »

if you look at this schematic ..it looks like the gasket goes over the header and inside the muffler. I went and looked at my 78 but a previous owner welded the header to the muffler.
On my 76 the set up is as a described. gasket over the header and inside the muffler.

https://www.servicehonda.com/oemparts/a ... 1a/muffler
Last edited by 5speed on Sat Jul 30, 2022 8:41 pm, edited 1 time in total.
1982 1100 standard. (sold)
1986 Yamaha FJ1200
2000 Yamaha Roadstar
1976 GoldWing. running but not on the road
1978 Goldwing. future cafe project.
2019 Can-Am ryker (boss's new ride)

2002 Shadow American Classic(sold)
1983 Shadow 500. (sold)
User avatar
pidjones
SUPER BIKER!!!!
SUPER BIKER!!!!
Posts: 3237
Joined: Wed May 22, 2013 4:06 pm
Location: East TN

Re: 78 GL1000 Exhaust

#7

Post by pidjones »

are you sure that all previous seal has been full removed? They can harden up and seem like steel.
"Love 'em all.... let God sort 'em out!"
Ex 2006 GL1800 - the Black Pearl SOLD! to make room for:
2021 Can-Am Spyder RT Limited Dark Chalk Metallic
1975 Red GL1000 project - ex Pistol Pete project
1972 Triumph T150V Trident rescue - finished and FOR SALE!
1976 Yamaha RD400c
1978 GL1000 with '75 engine - the Hunley
Ex 1978 GL1000
Ex 1979 GL1000
Ex '79 CB750F rat bike
Ex '86 SEi
Ex '77 GL1000
Ex '76 RD400
Ex '72 Penton 125 set up for flat track
Ex '73 RD250
Ex '68 TR6C - chopped
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: 78 GL1000 Exhaust

#8

Post by Lucien Harpress »

So, full disclosure I have a '76, which does have a different exhaust setup than the later '78/'79. That said, you're very close with A., with some caveats.

First off, the headers are the innermost part of that whole joint. Next up comes the gasket/packing/what have you- this fits OVER the rear end of the header, and INTO the opening of the muffler. Now, it probably bottoms out on the inside of the muffler, as you said, and this should be fine- the excess should project forward onto the outside of the header.

Next layer out is the openings on the front of the muffler. These should be split, or have cuts down the side in order to "splay" them open enough to get the headers and the packing to fit inside. Opening them up doesn't have to be perfect, just so there's enough room to fit the packing and header inside. Just be careful not to break them off- the metal is thin, old, and a common failure point.

The final piece that goes over everything is the clamp. The "teeth" you see on the clamp itself should go towards the forward edge (as your sitting on the bike, so facing the headers) and clip over the front edge of the MUFFLER- that part you opened up to get everything to fit inside. As you tighten the clamp down, the tangs on the muffler openings should close down on the packing/gasket, sealing the muffler to the gasket, and the gasket to the header.

The trick is to give yourself enough slop to get the entire assembly ready, but still have it fit all the mounting points on the bike. If you're mixing and matching a "new" set of components, you may have to open up the muffler openings quite a bit to get everything lined up.

The way I usually do it is to get everything lightly assembled, sort of lift the whole assembly close to in place (4x4 wood blocks help if you're by yourself), get at least every header nut and muffler bolt started, then tighten the headers, tighten the muffler attachments (whacking it a few times to help line it up if necessary), THEN tightening the muffler clamps last.

One last bit of REALLY small technicalities if you're using stock clamps. Most people orient them facing outward, with the tightening bolt horizontal to the ground. It doesn't look bad, the bolts are easier to get to, and 99% of other bikes run them this way. However, from the factory the "correct" way was to rotate the clamps up and inward, so the bolt is perpendicular to the ground instead. It makes for a "cleaner" look, at the cost of of the bolt being much harder to get to. Does this affect any of the above information in any way? Not really.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

Re: 78 GL1000 Exhaust

#9

Post by redsrback6 »

To Whiskerfish, PidJones, 5Speed and Lucien, guys I cannot thank you enough for all this detail. So grateful. Before your responses I spent the weekend trying to cleanup these parts. There was some super-light rusting of the mufflers, the headers weren't bad but I don't think they'd ever been apart from the shields and the underside of them was rusty. The left header was also skewed inward a bit at the muffler tip so I've straightened that out, probably from the aftermarkets, and as Lucien mentions I've flared the muffler tips a bit so the seals will fit better and hopefully fit over the header easier. Tomorrow I should be in position to make another attempt at this and I'll use Lucien's other suggestion by installing as a loosely connected unit. Btw, I'm attaching a very bad drawing I did after my first attempt. Pay no attention to the crosspiece connection as it was drawn pointing upwards. Nor did I draw the clamps. I'll report back soon, again Thank You All!
Attachments
image_50388993.JPG
image_50388993.JPG (121.8 KiB) Viewed 512 times
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

Re: 78 GL1000 Exhaust

#10

Post by redsrback6 »

Lucien/Anybody, I didn't exactly assemble the header and muffler and try mounting as a unit, that was my next step but... I did remount the left header letting it hang loose as possible, then I was able to slide the muffler on as far as it can go. The Honda gasket/seal butts up against the outer ridge of the header and the muffler inside wall. Should also note that the header actually extends into the muffler wall area by about 1/4 inch, diameters are almost exact fit. Unfortunately, I am still long by approx. 3/8 of an inch give or take. The holes of the muffler bracket and passenger peg/frame where it mounts, intersect but only by less than 1/8 inch.

So, unless I'm missing something, to me these OEM seals are just too long. I'd give anything to find someone with a 78 or 79 with stock headers and mufflers, who has mounted their exhausts using these seals to let me know they work.

I'm attaching 2 pictures, the wood background shows a 78 assembly I copied from eBay, and mine (purple rug) which I tried the same view to match. So you can see the seal is as tight as it will go, I've left off the clamp. Again, notice how far onto the header the eBay muffler slides, actually up over the ridge where the clamp locks. Again, there is no sign of any seal. Also, this may be significant... there are 3 nubs on the outside end of the muffler. I'm assuming these nubs help secure the clamp to the muffler side of joint while the clamp teeth then clamps over the header ridge. In my setup using the recommended OEM seal will position the clamp on top of these nubs. Not saying this is incorrect because I suppose the nubs will help apply pressure against the joint but the way the eBay mount is done, to me, locks the pieces together.

These seals are correct according to Partzilla, as well as the schematic Whiskerfish attached. Again they are approx. 13/16 in width. Questioning these seals period. Because there appears to be very precise overlap where the pipe ends actually tuck into the muffler inner wall of same diameter. Next thought is can these seals be cut to fit? Perhaps if I push hard enough I can get the seal to squeeze over top of the header ridge, buying some room.

Thank You!!
Attachments
image_67233793.JPG
image_67233793.JPG (229.15 KiB) Viewed 465 times
gl1000-left-exhaust2.jpg
gl1000-left-exhaust2.jpg (96.88 KiB) Viewed 465 times
User avatar
5speed
Honored Life Member
Honored Life Member
Posts: 5311
Joined: Sat Jul 11, 2015 2:37 pm
Location: Nova Scotia Canada

Re: 78 GL1000 Exhaust

#11

Post by 5speed »

I'd trim the seals with tin snips and call it a day.
1982 1100 standard. (sold)
1986 Yamaha FJ1200
2000 Yamaha Roadstar
1976 GoldWing. running but not on the road
1978 Goldwing. future cafe project.
2019 Can-Am ryker (boss's new ride)

2002 Shadow American Classic(sold)
1983 Shadow 500. (sold)
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

Re: 78 GL1000 Exhaust

#12

Post by redsrback6 »

TY 5speed, likely what I'll do! This inner wall of the muffler that header slides into partially has the same diameter and thickness as the seal. If I didn't use the seals but instead overlapped like the eBay pipes, that nearly butts the outer ridge of the header up against the inner muffler wall for an added seal.

Something else odd... the right side muffler actually has a deeper pocket for a seal to bottom out against the inner wall. So the seal would actually fit the right side! The 2 crossover connections fit exactly like the left side, though I don't yet know if length is an issue with crossover or not.
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: 78 GL1000 Exhaust

#13

Post by Lucien Harpress »

Yeah, that's odd. If the seal bottoming out is the only thing preventing the header from sliding in all the way, I'd just cut it down too. It's assembled correctly, far as I can tell, so I'm not sure why it's not fitting.

Ah well. The joys of fixing 40 year old machines.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
User avatar
pidjones
SUPER BIKER!!!!
SUPER BIKER!!!!
Posts: 3237
Joined: Wed May 22, 2013 4:06 pm
Location: East TN

Re: 78 GL1000 Exhaust

#14

Post by pidjones »

I had to chisel hardened gasket out of my mufflers for everything to fit.
"Love 'em all.... let God sort 'em out!"
Ex 2006 GL1800 - the Black Pearl SOLD! to make room for:
2021 Can-Am Spyder RT Limited Dark Chalk Metallic
1975 Red GL1000 project - ex Pistol Pete project
1972 Triumph T150V Trident rescue - finished and FOR SALE!
1976 Yamaha RD400c
1978 GL1000 with '75 engine - the Hunley
Ex 1978 GL1000
Ex 1979 GL1000
Ex '79 CB750F rat bike
Ex '86 SEi
Ex '77 GL1000
Ex '76 RD400
Ex '72 Penton 125 set up for flat track
Ex '73 RD250
Ex '68 TR6C - chopped
redsrback6
Zinc Member
Zinc Member
Posts: 51
Joined: Thu Oct 27, 2016 10:00 am

Re: 78 GL1000 Exhaust

#15

Post by redsrback6 »

OMG!!! I am an idiot! Owe you guys my deepest apology. PidJones, you are dead on man! All this time I've been looking at old seals thinking they were part of an interior wall of the muffler. I even got my dremel out and wire-brushed them and the crevice up against, assuming the seals needed to butt up against. The material is obviously baked on rock hard, looks so neat and permanent. Cannot believe it! Think I've been on this for a week at least. After your comments (again!) I went out to the garage and turned the left muffler on its tail end to shine my light down it. There is a 1.5 inch wall leading to another layer of metal tubing and perforated metal tubing. But... actually shining my light down it enabled me to see the break in the 1.5 inches. That first inch (slightly less) HAS to be the old seal/gasket. I'd left the new seal in it butting right up against the old, you can tell they are same size. The other 1/2 inch material must the normal bottom out piece of the muffler for the seal to sit against. Crossover tube... both ends also still contain the old. Evidently the old seal was NOT left in the right muffler or never had one, if you recall me saying it was deeper and looked like the seal would work fine there.

Again I want to thank each of you for using up your valuable time to share with me your knowledge and experience. Absolutely I would have gone a lesser route had you not helped me.
Post Reply
  • Similar Topics
    Replies
    Views
    Last post

Return to “GoldWing Tech Discussions”