My headers blew up!

So background on my bike, it had header wrap on when I bought it. My right leg was always hot so I got a RSS, which helped but my leg still got really hot when I was going around on city streets with 35 MPH speed limits in the summer.

The header wrap was black and eventually faded. When it did, I figured I might as well change it out for some lava wrap. Well when I peeled off the old wrap I found a nice crack on the front header, right around the backside of the sharp bend. Someone had done a poor job trying to weld it in the past and it was still cracked and leaking. Because of its location it could not be welded without removing the headers. I decided to use some stuff to repair the crack; it was a paste specifically made to repair exhaust manifolds, heads, etc, up to 2400 degrees continuous.

Fast forward to the next day (had to give the paste time to cure). I took off for work, seemed to be running normal. Filled up at the local gas station within the first two miles. A few miles after that the bike began sputtering and popping out the exhaust. It didn't want to go above 3500 RPM. It almost stalled at stoplights. I called my boss and said I would be late, and stuck to backroads where I could stay at slow speeds. The poor running condition was coming and going; sometimes I had to give it gas to keep it alive at stoplights, sometimes it seemed to be running normal.

About 10 miles down the road, there was a big bang out of the exhaust and my check engine light came on, but it seemed to be running fairly normal again. I was about 10 miles away from work so I figured I would keep going since I was almost there. Well, about a mile after the CEL came on, my bike started sounding like a WWII plane. I immediately pulled into a parking lot.

This is what I found.







Looks like Dean will be getting my business sooner than I expected.

So obviously I will be getting new headers, but anyone have some ideas on what caused it? A clog in the headers somehow? I had my Drummer apart a while back repairing the rivets that had torn through and it didn't have anything in it. The crack had a scuff near it so I was under the impression it had been laid over on the headers there causing the crack. Maybe bad gas? I have filled up at that station many times in the past and never had a problem before.

its happened to several people. dean can probably fix that header too. Ive seen some pics of others ones he has fixed that were way worse than that.

stressed metal and pressure would be my guess.

Get ready, header wrap rant incoming.

Siggh,,, Cause and Correlation, Theres several threads about header wraps, and while a exhaust CAN fail, generally because it had stresses from broken mounts or poor mounting I will go out on a limb and point out the obvious is that the wrap caused deterioration of the pipe untill it weakened and failed. Despite removing it, the damages were already done.
Look at most cars produced, they run a thick cast iron exhaust manifold, and have for decades. Exhaust gases consumer and eat away at the metal and studys show a linear consumption of the metal structure. This consumption of the metal correlates directly to the temps, More temp, more deterioration, less temp, less deterioration.
By wrapping your exhaust, or the DPO (Dreaded Previous Owner) it inhibits the metals ability to cool itself. I have seen a number of vehicles where the exhaust glows orange, nearly molten under hard running, by wrapping it you insulated it.
Conversely, by using a thermal ceramic coating, you coat the ID and the OD and creat a barrier between the exhaust gases and the metal. How many cars and trucks do you see stock from the manufacturer with thin wall exhaust pipes? NONE i am aware of. How many aftermarket exhaust manufacturers will honor their warranty's if a header wrap was used? NONE I am aware of.
Ive made this point again and again in postings and apparently Im considered idiotic for doing so, But empirical evidence doesn't lie.
Sorry about your situation, that sucks what happened. But if you want to know why, it was the header wrap. No doubt about it.

Header wrap rant delivered, my work here is done [smirk]

Dont just right it off as soully the header wrap. Common cause for your first crack noticed is the mounting of the exhaust. Does it have a factory pipe? Aftermarket? The front engine support bushings do go bad and vibration will cause tons of damage. Another thing to consider when installing a new header, replace your exhaust studs, they could be weakend and stressed, do it now and reduce your chances of sheering one, that leads to head removal and machine work. Good luck! Ive gad this problem going home from vegas with 300 miles ahead of me... Ended badly.

Thats a good point, buy a set of the upgraded exhaust studs while you are at it. renew all your mounts and straps too.

I figured this might start a header wrap debate. I think the wrap may have fatigued the pipe but I'm more worried about why it was running like crap prior to the blowout. I'll give all the bushings a checking over tomorrow. No question about the exhaust studs, I have dealt with broken ones on cars before and I would rather avoid it whenever possible.

More background info, it is a 2005 12Scg, just passed 22k miles. K&N, open intake, old Drummer exhaust. I used ECMSpy to load a race map on when I did the open airbox and adjusted it with about a week's worth of datalogs before my laptop decided it didn't like riding in my backpack and died. Guess it is time to get the Palm version.

There was always a little popping on decel but just small pops and only a few of them.

Dean could probably fix my header but it was in pretty rough shape before the sensor was ejected; I would much rather take this opportunity to upgrade.

Im sure Dean would welcome an order for a new exhaust system!!

As far as repairs, its sounds like you are sensibly NOT going to waste your time with that, and I applaud that decision, the reason why is that the metal was clearly fatigued. Even if you welded it Im certain it would break again.
Theres a process where when a weld is done on carbonized metal like that it causes embrittlement and granular crystallization. When welding, there will be stressed areas adjacent to each weld It would likely fracture again next to each weld.
many people are aware of consumables such as tires, filters and oil. things you factor in as a periodic replacement item. But, in aircraft applications many parts are time change items. Ive spent a lot of time destroying parts that looked serviceable to ensure they were not refurbished and returned to the supply chain. Certain engine parts, Landing gear components, Wheels, windscreens,Controls and flight surfaces etc etc all get changed out after so many hours. studys show the parts can only handle the stress of operation for so long before its time to replace.
Time to round file that exhaust pipe.

Join hands, Lets all moan a prayer to the wailing sisters of the church of the Hydrocarbon. Amen.

I meant to add,, that likely your exhaust started sucking in ambient air, either from the crack, or a leak somewhere.

If you add fresh ambient air into the exhaust like that its like the afterburner of a F16 on take off. SUPER HOT!!!
Your sensor picked up on the change and freaked out,, tried compensating, and possibly made it worse, a slippery slope.

Look at a Oxy/acetelyne cutting torch. when you fire it up with just the Acetelyne and crack open the valve,, you get a sooty yellow flame with black smoke, Add Oxygen and it becomes super hot and concentrated. Add even more Oxygen when you hit the cutting lever and it goes into hyperdrive and you can cut Steel like butter. No different than your exhaust.

I build vintage bikes. and when im done with a restoration or a custom. (Triumph, BSA, Norton) I keep sets of old **** pipes hanging in storage, I fire up the bike and do all my adjustments on the old pipes, adjust the carbs, time it. do the break in REVS (to break in the cams) all on the **** pipes, then we do the short rides, retorques, more rides until we get 150-200 miles on it. Then and only then do i install the new shiny exhaust. I have the new pipes (usually chrome) ceramic coated on the ID with the thermal barrier ceramic coatings. As long as you dont allow leaks, the pipes will NOT blue.

I get comments at shows sometimes. "Nice bike, shame he doesnt ride it" When people dont see the blued exhausts they assume I dont ride the things. Oh well... Some of the exhausts are very expensive. And i like to keep them that way (Unblued). But IF you do get a leak... even a ceramic coated exhaust cant fight that off for very long.

Someone had done a poor job trying to weld it in the past and it was still cracked and leaking.

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There's your problem NOT header wrap. Whoever previously owned the bike rode the piss out of it hard enough to cause stress cracks,then instead of replacing the header they did a shoddy weld repair,wrapped it up and sold it to you.
Spend all the money you want on aftermarket overpriced crap but don't blame header wrap on someone's elses poor decision and maintenence.

This is header wrap induced fatigue failure, at least to me.







Vibration probably caused this though.



Yes, it can be fixed. Not pretty, but it will work.







PS. Give me a couple of weeks to get caught up some, I hit my limit yesterday and am still getting emails and calls about ordering exhaust systems. I know you need one asap, but I'm at 6 weeks worth of work and really need to knock a bunch of this stuff out. I'll be cutting out of work early today just to get a longer weekend for playing in the garage.

When people dont see the blued exhausts they assume I dont ride the things.   Oh well... Some of the exhausts are very expensive. And i like to keep them that way (Unblued). 

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Haha, how things change!

My Dad rode British bikes (Matchless & AJS) in the 50s & 60s in the UK. Back then they would actually use gas torches to accelerate the bluing of their headers! Unblued pipes were considered like chicken strips; a tell-tale that the bike's owner didn't ride hard. The bluer the better!

Annoyance, I have to say I thoroughly enjoy the amount of detail you always provide. (I'm not being a smartass here.) One of the reasons I appreciate this forum is the amount of knowledge put out there for us all to either learn from or ignore completely.

And I have to say you've convinced me. It's time to wrap the INSIDE of my headers as well. Now where's my dual-articulating mirror-wand???

This is exactly how the crack is that was covered up, just on the engine side of the header.

Dean, I know you've got work to do. Don't feel rushed on my behalf. I have a truck to get around in, so its not a necessity to fix it right away, I can still get around. It just isn't as fun.

Whether or not it was wrap-induced doesn't bother me all that much. Yes I wish I had known about it before I got the bike and I should have checked. Some nice headers were on my wish list anyway, they were just down towards the bottom, now they have moved up. On the plus side now I will be able to check my front AFRs.

So, this?




Or this?



1st one is 1.88", will not clear a RSS, 2nd is 1.75" and will clear one.

Much as I'd love to go big or go home, I need my RSS so I'm leaning towards the second. Besides, my internals are all stock so the extra diameter isn't really needed.

Needs a couple more little things (springs/retainers) and it will be ready.

Just happened to me!

Had mine fixed, reinstalled today.

Will post up some "after" pics bit later.

Good luck!