Exhaust header woe... (includes non-potato pics)

[carvell]

My bike failed its MOT today because the header pipes are leaking excessively. It's making the bike splutter on the overrun and makes it sound like the engine is knackered (makes a noise that sounds like the top end is knocking).

The MOT tester said that at first listen he thought the engine had had it but was then relieved for me when he saw that it was blowing at the header pipes.

Some pics attached below.

Do I need to buy new header pipes? It doesn't look very weldable there.

Also, there should be a seal between the pipe and the engine. I can't see one. Am I being blind? Is it still wedged in the cylinder head?

Anyone got any experience of using that gunky weldy stuff in this position? Did it last more than 100 miles?

Thanks!

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Yamaha TDM 850

[P.addy]

Do you have access to a welder?

I'd think a few seconds and that would be perfect again, subject to the surrounding material being ok.

[Andy_Pagin]

[c_dug]

Chemical metal would get it through an MOT.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[P.addy]

I'm dubious with chemical metal so close to the exhaust outlet myself... and I like to bodge.

[carvell]

[Hugh Farking Cant]

You have done the hard work; getting them off without goosing the studs.

Take them to someone with a mig welder and give him a six pack for the 5 mins work it will take to make them last another good few years.

When you get them home , spend £8 on a tin of VHT or BBQ paint and make a proper job of it.

Better still would be a trip to the powder coater.

That looks like the copper gasket is flattened in the ex.port

Don't forget the copperslip on the rebuilt.


Chemical metal is more for mending pots and pans when tinkers are in short supply.

Just going to ask ; 849cc on block, is that a TDM ? but then clocked your avatar= mk 2

[c_dug]

Never suggested it was anything more than a bodge but I'd happily use chemical metal on it the night before the MOT in the knowledge that it will blow out within a week. Takes the pressure off getting it welded so quickly and prevents having the bike off the road for those of us who need one daily.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[nowhere.elysium]

This is exactly the sort of thing that Holt's Gun Gum is designed for.
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'10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project

[carvell]

[Hugh Farking Cant]

[gavcarter]

[gavcarter]

in fact fuck it - just wedge a little chunk of potato in there!
https://odditymall.com/includes/content/potato-french-fry-cutter-0.jpg

[stinkwheel]

[Andy_Pagin]

[carvell]

Noted, thanks all! The carvell welding plan is off!

I think what I'll do is put some gun gum stuff on it to get it through the MOT retest for free, then take the headers to a 'competent' person in slow time.

Saves me spunking money on a welder only to be disappointed anyway.
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Yamaha TDM 850

[Hugh Farking Cant]

Any one contemplating buying a mig welder;

Get the ones with a variable rotory dial for amperage rather than the type with two rocker switches.(not enough combinations)

They are much more controllable.(you can go much lower)
Unfortunately they are usually the higher amperage ones.
Avoid gasless unless you are a farmer.

Many are put off higher amperage welders by the amperage supplied by their house hold supply needed to run them at higher rates= 140 amps is about it before blowing fuses .(13 amp household = 140 amp max welder)

Most can get round this by getting a supply from the electric cooker circuit extended. (circa 30 amps) which opens up the choices considerably.

[Jim painter]

If you do decide to go down the welding route get a piece of copper plate behind where your welding. That way your less likely to blow through as the copper is there as a backup, plus the weld pool won't stick to the copper. This gives a clean flat weld inside the pipe so not to disrupt the exhaust gases, you should be able to flat the weld on the outside of the pipe as well.

Jim

[WD Forte]

Good tip about the copper but as there's an overlap,
I'd use some small pieces of say 1 to 2mm shaped plate inside
to help beef it up a bit.
There'd be no added or significant restriction to the pipe and as in my experience, these holes often get bigger at first when to you try to weld them shut, it gives you some wiggle room.
Afterwards some nifty use of an inox disc then maybe a trim with a file
will help get the contour back so the collar fits well.

I wouldn' bet on gum gun or JB weld for a long term fix
GG has little or no mechanical strength and JB weld
may not like the temps
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bikers smell of wee

[Pete.]

You don't need copper, a slug of aluminium will do just as well. Just don't make it too tight a fit and do make sure you clean up the inside so there's good thermal transfer. A temporary fix with any kind of resin would be very temporary and would not make the welder love you when you come to make a permanent one.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Rogerborg]

YES, there are crush gaskets in there. They are designed precisely to squash down and create a tight seal, but once you start stabbing and hacking you'll quickly find a joint.

NO, you cannot fix that with an arc welder.

No, YOU cannot fix that with a MIG welder on your first go. Probably.

YES now that you've got them off, that's 10 minutes work for a pro, including prep.

YES you could bodge it for the MOT. I'd go with a smear of gun-gum or exhaust assembly paste, a strip of baked bean tin (MUST be Heinz), and a jubilee clip to hold it together. Get your ticket for the year, then sort it properly at your leisure.

EFF bodging exhausts though, there's no bottom to that well. You'll end up replacing it sooner or later, and the sooner you do it, the less time you'll piss away on it.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Robby]

Welding that may be trickier than it looks. If all of the metal around it has gone paper thin then it isn't worth welding. Could be worth trying to braze in a very small patch from the other side, but you would need to be sure that the exhaust won't get hot enough to melt the braze.

Anything would be a temp fix. Once an exhaust rusts through in that sort of area the rest of it is close behind.

[carvell]

[Robby]

Stainless headers won't stay shiny for long. After a bit of riding the heat cycles will colour the steel, and road crap will make them look filthy in no time.

[UK-Badger]

I had exactly the same problem and it took less than 5 mins to MIG weld with no filing needed. The repair lasted with no issues. Don't try and weld it all in one go, build it up a bit at a time allowing it to cool a little in between.

Of course when you put it back on be sure to use new crush washers..
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Triumph Street Triple & Suzuki SV650S