Anyone ever seen an exhaust do this?

[djh3]

So my Victory has had some popping on deceleration for awhile now. I have been thru months of troubleshooting another problem I got fixed, and part of it started with an IAC valve. So a couple days ago I stopped at the store and when I mounted up to come home being it is only a couple blocks or so I skipped the ear plugs. I noticed what sounded like the old exhaust noise from the small blocks when the doughnuts blew out. Looked around and here is what I found.

[Marcarl]

Looks like maybe something went BANG. One of those backfires too much.

[saddlebum]

I once had a back fire so bad I felt the back of my car lift slightly and afterwards my exhaust sounded like wide open pipes. The backfire was so severe that it split my muffler wide open as well as lifting the back end. What happened was while driving on the highway a transport hit a massive puddle and my car caught the splash which killed the engine for a split second causing my exhaust to accumulate a fair amount of raw fuel. When the engine fired up the raw fuel mix in my exhaust ignited and went off like a stick of TNT.

[uncledj]

I dunno.....I'd call it excessive heat....Looks like it'd be easy enough to mig weld it together and wrap it back up, but without any other changes it'd likely happen again.

Edited August 21, 2022 by uncledj

[Pasta Burner]

Wrap might not be doing you any favors there.

[saddlebum]

On 8/20/2022 at 8:24 PM, uncledj said:

I dunno.....I'd call it excessive heat....Looks like it'd be easy enough to mig weld it together and wrap it back up, but without any other changes it'd likely happen again.

If the exhaust is getting that hot 🔥  you may have a lean burn condition and/or a leaky exhaust valve. Leaky valve is easy to check by doing a cylinder leak down test. Valve adjustment, deteriorating valve or valve seat condition, or sticky valve can all be causes of a valve leakage. Also check your plugs colour and compare to a plug colour chart. 

Edited August 22, 2022 by saddlebum

[BadCatClassics]

The wrap and a lean carb stressed the metal. Don't repair replace it and don't run the wrap.

[djh3]

Well cant be a lean carb as bike is FI. I have located a set of used OEM pipes and I am going to VHT paint them and whap wrap is on them is coming off. I dont think it hurt anything, but I'm not going to chance it. Mostly it is falling apart anyways. I hope the coating will help a little with paint. The "crossover" on the Cross Country contains the catalytic converter, and I have been tempted to take it out, but over the years I have come to figure out they are designed with that and if you take it out bad things can happen. And I dont want to go the fuel controller route and have to manually tune things.

[BadCatClassics]

1 hour ago, djh3 said:

Well cant be a lean carb as bike is FI. I have located a set of used OEM pipes and I am going to VHT paint them and whap wrap is on them is coming off. I dont think it hurt anything, but I'm not going to chance it. Mostly it is falling apart anyways. I hope the coating will help a little with paint. The "crossover" on the Cross Country contains the catalytic converter, and I have been tempted to take it out, but over the years I have come to figure out they are designed with that and if you take it out bad things can happen. And I dont want to go the fuel controller route and have to manually tune things.

Fuel injection can most certainly run lean and is often very lean from the factory to meet emissions. The wrap retains heat at a level the exhaust designers did not account for. 

A normal backfire cannot cause that kind of damage.

[djh3]

Have a "new" set of take offs. I was going to pull the heat shields and paint them with VHT, then put shields back on. I try to think about doing it and say "ah heck skip it" While FI "could" run lean more times then not the ECM will not let it run lean enough to hurt itself. It is a single wire O2 so if disconnect them it will fatten up the mix a tick and not set lights. I ran it that while a few years back to see if I could get it to run a bit cooler. I couldnt tell any difference.