Author Topic: [FIXED] Dent/hole in exhaust header  (Read 1879 times)

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Offline sammermpc

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[FIXED] Dent/hole in exhaust header
« on: January 24, 2016, 09:12:54 AM »
I've got a small dent in one of my exhaust headers. It ends, actually, in a very small hole — looks like it may have been caused by a rock or something.

I filled it once w/ a high-temperature steel epoxy, before painting, but unfortunately, the entire filling popped out after a few rides.

Any recommendations about how to best go about repairing it so it can be smoothly painted over again? I don't want to wrap the headers, and otherwise, they are in pretty good shape, I think). I've seen people talk about brazing — anyone know more about that?

« Last Edit: February 26, 2016, 05:09:32 AM by sammermpc »
1972 CB500, 1979 CB750F SS (dohc), 1982 Yamaha Maxim XS400

Offline grcamna2

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Re: Dent/hole in exhaust header
« Reply #1 on: January 24, 2016, 09:15:10 AM »
Do you have a pic? is it an aftermarket pipe or oem ?
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Offline sammermpc

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Re: Dent/hole in exhaust header
« Reply #2 on: January 24, 2016, 09:38:26 AM »
Not OEM. It's a 4-into-1 — I don't know the model. Here's a pic of the bottom, showing the dent:



I don't know if I've got a great picture of the whole pipes, but here they are before I painted em' the first time around:

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Offline Draybot

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Re: Dent/hole in exhaust header
« Reply #3 on: January 24, 2016, 09:42:33 AM »
Ooo, I just discovered a very similar hole in my 341's,  interested in seeing how this repair goes! Best of luck.

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Offline grcamna2

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Re: Dent/hole in exhaust header
« Reply #4 on: January 24, 2016, 09:47:20 AM »
That's a nice looking classic style header and I would certainly repair that one  8) ;if it was mine,I would have a welder drill at least 1 small hole in the dent and then heat it up and pull it out some.Dents can reduce performance somewhat if you are going 'all-out' for high performance that is.. I would then braze/tig the little holes shut and sort of fill it in w/ braze until it's smooth.I would then have the header PC'd w/ high heat ceramic PC  8) if it was mine..
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Offline mystic_1

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Re: Dent/hole in exhaust header
« Reply #5 on: January 24, 2016, 09:49:59 AM »
Really I think that repair of that hole would take just a couple of minutes with a welder, and other methods may not be worth the time investment.  Brazing would work, but isn't really saving you anything in terms of effort or cost.

Especially given the location, and the fact that you can repaint over the repair.

Filling that dent with anything will, i think, always be a failing proposition.  The pipes are pretty hot there still, you can get away with stuff like that back on the mufflers but you'll need something that can handle very very high temperatures in that location.

Stick a long rod up there and see if you can bang out the dent, then weld up the hole or have it welded, would be my suggestion.

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Offline rb550four

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Re: Dent/hole in exhaust header
« Reply #6 on: January 24, 2016, 09:56:29 AM »
  Looks like it's had some rust on it and in it? I had a pipe in similar condition , decided to hit it with a welder, a 110 30 amp home use , not a 220v Lincoln arc, didn't matter, more chrome left on the outside of the pipe than metal on the inside, the holes got bigger until there was enough metal to weld to.... could have left it alone being it wasn't perfect , now it's totally unusable. I guess if there was an easy answer we wouldn't all be looking for new pipes.   Good luck.
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Offline cougar

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Re: Dent/hole in exhaust header
« Reply #7 on: January 24, 2016, 10:09:20 AM »
sam ; I agree with "mystic_1" in that I would try to round that area back out if Absolute performance was being sought after or looks. Beyond that Yes that could be welded up and ground down to look smooth again. If it were my pipe that's exactly what I'd do, here at home.   ...cougar...    P.S. If you were local to me (Stamping Ground,Ky.) I'd do it just for a visit  :D !
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Offline grcamna2

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Re: Dent/hole in exhaust header
« Reply #8 on: January 24, 2016, 10:22:15 AM »
sam ; I agree with "mystic_1" in that I would try to round that area back out if Absolute performance was being sought after or looks. Beyond that Yes that could be welded up and ground down to look smooth again. If it were my pipe that's exactly what I'd do, here at home.   ...cougar...    P.S. If you were local to me (Stamping Ground,Ky.) I'd do it just for a visit  :D !

Now That's being neighborly  ;)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline sammermpc

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Re: Dent/hole in exhaust header
« Reply #9 on: January 24, 2016, 10:44:18 AM »
Thanks for the offer! Wish I could take you up on it.

The pipes have seen some rust, but overall they are pretty solid. The dent (and hole) is very much caused from impact, not corrosion. All the same, how concerned should I be about what rb550four is talking about? That's why I asked about brazing -- my understanding is that it's lower temp so safer?

Performance wise, considering that before I tried to fill it, I was riding w the open hole, I guess I am not too picky. That's a good thought to knock it out w a long rod, then weld it.
1972 CB500, 1979 CB750F SS (dohc), 1982 Yamaha Maxim XS400

Offline grcamna2

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Re: Dent/hole in exhaust header
« Reply #10 on: January 24, 2016, 10:57:38 AM »
sammer,
How far away do you live from a true vintage motorcycle friendly repair shop or a fair and encouraging welder who respects vintage Japanese bikes ? I would remove the header section and take it to one of them to inspect,they can shine a light into it to check it out,etc. Have you considered high temp powder coating ?
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline 754

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Re: Dent/hole in exhaust header
« Reply #11 on: January 24, 2016, 11:32:45 AM »
Weld a rod to middle of dent, heat sround it and pull up, then weld the hole..
 They are thin, wont last another 40 years..
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Offline grcamna2

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Re: Dent/hole in exhaust header
« Reply #12 on: January 24, 2016, 11:49:38 AM »
Weld a rod to middle of dent, heat sround it and pull up, then weld the hole..
 They are thin, wont last another 40 years..

that sounds like an excellent way to repair it
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline chewbacca5000

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Re: Dent/hole in exhaust header
« Reply #13 on: January 24, 2016, 12:01:53 PM »
I welded up some headers for my C300 using a Lincoln 22nd arc welder with 6013 rod set to 40 amp.  It was the smallest size they sell at lowes.  It worked, but fitment needs to be near perfect.  I melted though several times.  Tiger that allows you to dial down to 20 amps or so would be great.  I got one new never used just have not bothered getting gas for it

Offline 754

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Re: Dent/hole in exhaust header
« Reply #14 on: January 24, 2016, 12:20:36 PM »
Use oxy Acet..
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Offline sammermpc

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Re: Dent/hole in exhaust header
« Reply #15 on: February 26, 2016, 05:09:10 AM »
Just a quick update — took the pipes to a buddy of mine who knows his way around a TIG, and we got things patched up. First we drilled out the, and then shaped a little patch of steel to cover, before welding it down and shaping it.

We were kind've experimenting, but I'm really pleased how it came out. I have a whole new respect for welding.





Shaped patch...things are looking a bit questionable.



The bottom of the patch was feathered, so it sat sort've inside of the hole. Welding it down melted it downwards, a bit, and it sat a lot flusher than before.




After some shaping, it looks really good — it won't be noticeable after sanding And given the fact that this is way under the bike :D
« Last Edit: February 26, 2016, 06:49:01 AM by sammermpc »
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Offline evanphi

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Re: [FIXED] Dent/hole in exhaust header
« Reply #16 on: February 26, 2016, 05:34:37 AM »
Looks nice and smooth
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