Mapp Torch brazing - experiences?

[A100man]

Might need to repair a crack in an exhaust flange.

Haven't ever brazed before (a bit of MIG work only) and I don't have any kit. I see though you can buy cheap Mapp compatible torches from ebay and the gas form toolstation.

Anyone done similar? and what filler rod did you use??

Cheers
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Now: A100, GT250A, XJ598, FZ750, SL1000

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600, Skorpion

[Riejufixing]

[ThatDippyTwat]

MAPP works for brazing - even the new wannabe MAPP works. Getting a torch tip that's focused enough is the key, most will have a wide tip and you'll struggle to get enough heat into a small area.

Cherry red is what you want. Flux is your friend. Ideally, shove it in an oven afterwards, and let it cool slowly, cast stuff likes to crack if it's thermally "shocked". Hot sand (disposable BBQ and tinfoil) also works.
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'98 VFR800 (touring) - '12 VFR800 Crosrunner (Commuting) - '01 KDX220 (Big Green Antisocial Machine)

[Hong Kong Phooey]

You might want to drill a hole at the end of the existing crack to stop it spreading.
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[A100man]

Thanks chaps - I guess we're not talking plumbers flux here are we?

This kind of stuff perhaps..

https://www.ebay.co.uk/itm/SILVER-BRAZING-SOLDER-FLUX-KIT-55-silver-Just-add-heat-5-x-200mm-rods/183864842166

Crack is in downpipe/flange not a casting so not sure about hole drilling
____________________
Now: A100, GT250A, XJ598, FZ750, SL1000

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600, Skorpion

[bikenut]

seen sifbronze rods on ebay with a pack of the pink coloured sifbronze flux.

tubs of sifbronze flux available from welding suppliers as are the rods, seperately......

seen the narrower flamed mapp gas burners on ebay and saving for one, the wider plummers blowtourch i have is not concentrated enough for brazing up a pin hole in a tank so soldered it instead, but yours is an exhaust pipe.......a header so will get quite hot, but hopefully not hot enough to affect the brazing repair.

maybe better to mig weld it....post a picture....
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nuts about bikes

[Robby]

Yes, I've done it lots of times.

Use MAPP gas, the other stuff for blowtorches isn't quite hot enough. Flux-coated rods make it easier, I got a load of them on ebay. The ones from halfords are good too.

[Riejufixing]

[Hong Kong Phooey]

I was presuming this was cast iron, which often cracks.
What is the thing made of?

Steel = weld
Cast or grey iron = braze
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[Riejufixing]

[A100man]

Yes it's steel. Wire feed is buggered on my Sealey Mig (well the one I have access too) I replaced the torch liner but still no dice so I've sidelined it - in any case I'd probably just have blown a hole in it

Thought brazing my prove an interesting thing to try and can be used to mess about with push bike frames too I'm told.

Will look out for sibronze rods then..

Cheers
____________________
Now: A100, GT250A, XJ598, FZ750, SL1000

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600, Skorpion

[Hong Kong Phooey]

Does wire feed ok if you remove the tip?
Use thinner wire for thinner metal, a flange is thick enough for 0.6mm.
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[bikenut]

maybe time for a new drive roller?

Finally got one for my very old now clarke and its fantastic again.

The old roller ( original to machine ) had developed a flat spot on the 0.6mm groove and had jerky stop go stop go feed, so weld was inconsistent and not pretty.

our local welding supplier ( she great and knows her onions !! ) is brilliant.
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nuts about bikes

[Hong Kong Phooey]

[A100man]

Its a while since I had it apart but i think it was still gash without a tip. I was suspecting the rollers/roller tension.. bit visually they look OK. probably worth a punt as it's not a bad tool when 'on song'. It was inherited from my dad but is kept at my brothers place..

..meanwhile brazing seems a compact solution for light jobs.
____________________
Now: A100, GT250A, XJ598, FZ750, SL1000

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600, Skorpion

[Pete.]