Topic: How should I fix this hole in my exhaust? CB750 4-to-1

[Tugboat]

Started cleaning up my pipes yesterday. Most of the rust comes off pretty easily with a wire wheel on a dremel. At some point I'm going to replace it entirely but I want to get a couple more years out of it before I do. So what should I do about the 2 small holes in the collector? Can I just JB Weld it? Would that hold up to the high temps there or should I have it actually welded or what? FYI I just blew pretty much my entire bike budget for the winter buying a replacement motor and associated gaskets etc, so I can't just throw money at this (like thats ever an option LOL).

[Skunk Stripe]

JB has been used to fix those holes. Just get the area well cleaned and then I would suggest using the regular jb, not the jbqwik.
Another option instead of jb is a putty called steelstick. It has other names too but you can get it at walmart and other auto parts stores.
It comes in a plastic tube and you just twist off what you need. Kneed it like dough till it is all one color and then stuff it in. I used it to hold the mirrors on a car and that was 2.5 years ago and it is still holding...By itself, no added screws or anything. I used it on a water faucet too and that was over 3 years ago and still no leaks.

[Kong]

Well, in the long-term sense there's nothing you can do about it.  See that little lip on the inside where the seam is folded over?  Well, one of the by-products of combustion is water and that little crevice there, which looks to run completely around the pipe, is where it can collect and start the rusting process from the inside out.  That means that what you see is not all you've got.  

That said the easiest fix - and it may last a year or so but no longer than that - is to braze it shut with brass rod and then paint it.  Just fine someone with a torch and buy yourself about a quarter pound of pre-fluxed brass rod at your local welding supply place and sit down and do it.  Its kind of like a cross between soldering and welding, good practice for the TIG torch though.  Brass can withstand the heat and will fill the hole.

[TwoTired]

I "repaired" a similar problem with a cb 550F muffler.  Since the metal is so thin at/near the rust through and contaminated, I brazed a tin patch over the hole, extending to a more solid area.  Worked far better than I expected, as I thought it was kind of a "hail Mary" before pitching it in the trash.  Do clean the outside well for best bond, as brazing is kinda like soldering, and adheres rather than blends with the parent material.

It's been over 15 year since a made those patches and to my surprise they are still gas tight.  Of course the chrome isn't pretty anymore.  But, that is what black paint is for, I reckon. 

Cheers,