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Discussion Starter · #1 ·
I removed the exhaust to install my new engine guards. Got the engine guards all done and reinstalled the exhaust. Fired up the AT and it is leaking at the flange where it fits into the head. I removed it again and didn't see anything that looked like an obstruction, so installed again, everything is lining up okay, torqued to 15 foot pounds per the service manual, and same result.

Am I missing something? Not holding my mouth right? Do I need to break apart the exhaust system into smaller, individual components and work my way to the muffler when I reinstall?

I appreciate any help or suggestions.

Bud...
 

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I removed the exhaust on my 2018 ATAS to install the Hepco & Becker lowers.

I remember getting it back on was a bit like one of those Chinese puzzles (I left it all whole, from the header pipes to the muffler). It took just a bit of finessing back and forth (I had supported the rear/ muffler with twine, so it was already close to where it needed to be) but it still took a bit of moving up and down and, presto, everything lined up and popped into place with a *very* noticeable motion.

I talked with my cousin (Motorcycle Technician) about the header flange bolts. When I removed them for the install, they seemed to be on pretty loose from the factory. But he advised 25 ft/lbs even though I told him the spec was lower. So I split the difference and I set my torque wrench for 20 ft/lbs and stopped *just* as I felt the wrench barely reach it's slip. I realize you have to be careful there, and too much pressure can bend and contort the flanges or seals.

It's hard for me to trust some torque wrenches when it comes to the lighter settings. Maybe just tighten the flange bolts just a *little bit* more? As long as you're *certain* everything is lined up well?

Mine are not on that tight. I even backed them out and in again to be sure; and the pressure I was using on the wrench was next to nothing. Somewhere between 15 and 20 ft/lbs.

I guess that's why I added the bit above about the pipes sort of snapping into place at the headers with a very noticeable sort of shift or transition with the whole thing in my hands--when it all lined up and went in at the front it was one of those things like, "Yes! Voilà!"

So, if you're sure you're all lined up well, maybe try to tighten the bolts just a *tad* more. (All the caveats about header flange bolts applying).

Good luck man. Hope it works out well! Gary

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The more I think about it, make sure you're not too tight?

Are you confident in your torque wrench? I've found they are much like thermometers in their accuracy. Like most of us, I have the big ft/lb and the smaller in/lb wrenches. I used the in/lb for this and converted.

But the real takeaway when I think about my exhaust removal and reinstall, is just how loose those flange nuts seemed when I first removed them; it seemed barely beyond finger tight from the factory--if it was 15 ft/lbs, it was just that and no more. Thus my backing down from my cousin's recommendation and torquing them down to just a hair tighter than what I believe was there prior. I backed out and re-screwed a couple of times to be sure they weren't on too tight.

But my bike had just a few hundred miles on it when I did the work so I wasn't going to replace the gaskets. However, as Jim shows in the manual above, Honda does recommend changing out the gaskets each time you remove the pipes. If your bike has lots of miles, new gaskets it is.

Let us know what you find out. Good luck, Gary

A few pics of when I worked on my bike... I did remove the shield but left everything else connected when I removed and replaced the exhaust. I marked the bolts where the flange sat after removing the nuts, but didn't really have to check that upon reinstall... as I mention, the whole thing sort of "snapped" into place when it was lined up with a very definitive "feel" and movement. And the flanges were easily pushed up flush against the header.

...
 

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Those exhaust gaskets are like the ones on about every other Honda made in the last 60-odd years; they're a soft copper donut, made of thin tubing with some kind of heatproof filler. They flatten right out, so if they've been used, they don't have any give left, especially if they've been overtightened. I myself would be afraid of pulling the threads out of the head by overtightening much past the spec.
 

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Discussion Starter · #6 ·
Sorry I have been away for a couple of days with a medical issue. I'm on the mend, but can't do any heavy lifting for another 5 days or so.

The bike only has 1200 miles, so the gaskets are very smooth and intact where the flange contacts them.

Gary, your pictures showed what I believe to be my problem. I am not getting the flange all the way into the resisted area. I need to find that sweet-spot you mention when "the whole thing sort of "snapped" into place."

I think when I get back to it, I'll disassemble the exhaust to as many smaller parts as possible. That should reduce the weight so a sickly ol' fart like me can handle it easier.

Thanks to you all for the responses. I'll update in about a week.

Later, Bud...
 

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Heal up, man.

I'm glad the pics helped. I hoped they would somehow.

And yes... I really wanted to get across what I experienced with mine when I went to replace. It didn't take long, but even though everything looked lined up, I had to jimmy up, down and around just a little bit until that *very* obvious clicking into place occurred. You *will* know it when you get it. It takes *no* forcing at all. Just patience and, like a Chinese puzzle, when you get it just right, it smoothly pops into place and stays (if you have the rear supported and all balanced well).

But if you can break it down to just the headers--I can't remember if the headers just slip into the collector or if it's welded or riveted or screwed--you'll probably find that sweet spot so much easier.

But don't despair if you have or want to leave it all together. Just use twine at the back to hang the muffler and hold most of the weight while you guide it in at front.

Good luck man. Get better and keep us posted. Gary

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I myself would be afraid of pulling the threads out of the head by overtightening much past the spec.

Man, I'd think it would take a whole lot more than 15 ft/lbs to dislodge those studs. But you're right. I've heard of them becoming dislodged. But I'm guessing people are tightening the nuts way too much or maybe knocking the studs around.

15 ft/lbs (or 20 ft/lbs for that matter) is pretty much just snug. With a foot long wrench, it's gently snugging up the nut.

The average man's arm weighs about 9 lbs (150 lb. man). My arm weighs about 12 lbs. So for 15 ft/lbs it's just a bit more than letting my arm hang on a 1 ft. wrench. For the avg. man, gently lay both arms on the end of a 1 ft. long wrench and you've over shot 15 ft/lbs by 3 lbs.

But like I said, a *big* takeaway from my exhaust removal/ reinstall was just how loose those (exhaust pipe joint) nuts were from the factory. I remember being a bit shocked at how easily they came off, like barely beyond finger tight. Thus I put mine back on very gently--somewhere just over 15 ft/lbs. But man, I wouldn't trust a big torque wrench (like a 10 to 150 ft/lb wrench) on nuts like this unless it was a decent deflecting beam wrench. I'd just go barely past snug or use a good in/lb or deflecting beam wrench (so you can really see what you're doing).

Gary


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I had a similar issue when trying to reinstall my headers after my skidplate install. I used a jack to hold the bottom of the exhaust and then thought it would be smart to loosely connect the rear hangar and then deal with the headers. There was no way that was going to work, so I disconnected the rear hangar and relied on the jack to hold most of the weight. I found that lowering the rear of the exhaust much more than you think you should, and bringing it slightly away from the bike allowed the header to slide right into place.

I didn't want to worry about them, so I purchased new gaskets even though the bike has less than 2,000 miles on it. Keeping them in between the head and the header made finagling everything even more difficult as they kept falling out every time I moved the header around. I'm a bit worried that I may have over tightened the nuts, but haven't had a chance to ride the bike since, so I guess only time will tell. If I ever take the exhaust off again I'm definitely breaking it into smaller pieces.
 

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Americans all complain about how Japanese fasteners are made so soft that they snap easily, but there's a reason: the aluminum castings are softer than the iron customarily used in American stuff, and it's cheaper to replace the fastener than repair the threads. So they spec a low torque value. And also the aluminum deforms under pressure easier than iron, so you don't need as much clamping force. American bolts are hard because they may rust into the hole, and you need to moose them out.
 

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Discussion Starter · #11 ·
Okay, it's fixed! The flange must be inside the recessed area at the head. I never got the clicking sound or an obvious notice that it was actually in; it would also slip out when I removed the pressure to hold it in place (needed a third hand). So a visual examination was necessary to insure it was actually in place. The cap nuts can only go on till the stud bottoms out in the nut. Over-torquing is not required to seal the fitting - only proper fitment. 15 ft. lbs. is more than adequate.

I really appreciate the suggestions and guidance I received. Thanks Much to all.

Now if the weather clears maybe I can go for a ride tomorrow.

Later, Bud...
 

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This was a timely thread for me! I got my stainless steel Hepco and Becker lowers and will be installing them on my ATAS in the next couple of weeks. I did order new exhaust gaskets and will replace them when I go back on with the exhaust. If I learn anything additional that will benefit the thread I'll post it up. Thanks to to everyone who contributed.
 

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Great news, Lowrider.

Yes, the gaskets are recessed.

And there wasn’t any real “clicking” noise, per se, it was just an obvious movement/ shifting into place.

Ps. I’ll keep everyone updated on my gasket seals over time; if I have any issues in the future.

Shadowjack is too right about those gaskets though. They seem more like clay than rubber.

I think I probably got away with it, but I wouldn’t advise it to anyone else. Worth a try on a new bike, sure, but not ideal.

I'm hoping because the seal was so “loose,” the nuts so lightly torqued and my careful retightening, that the pipes went in and married up to those malleable gaskets just as they had been and it works out ok.

But after completing the install she purred like a kitten; (immediately after the work I fired up and listened carefully near the headers for any leaking and then went for a test ride).

But more importantly, I rode it for about another 700 miles after the work with a few off-road excursions and so far, so good.


Oh, and Pps…

You guys really should try the twine trick when removing and reinstalling the exhaust. My cousin advised it and like most simple tricks, it works incredibly well. I didn't have any problem with the weight of it all, set up like that. (And I’m not as strong as I used to be either). And getting it off took just minutes. Back on, the same. It took an hour or so to get the H&B lowers on, but the exhaust was easy and quick.

With the rear portion hanging and holding all that weight, manipulating and hefting the header end was really easy.

I then lined up the pipes and pushed toward the cylinder heads to mate up, but noticed right away it didn't feel right, even though the pipes appeared to be lined up well with the heads (at this point, the flanges were hanging down the pipes, out of the way, so I had a pretty clear view).

I can't remember the exact manipulation that made it work for me but I'm guessing, after reading about your experience Motorwerx, that because I had the rear tied off and hanging and lined up about right where it would eventually connect but having slack enough there to move the rear away from the bike and down just a bit, that's probably what I ended up doing.

Here’s a picture of where I had the twine hanging, just to get an idea. But this is *prior* to removal. I put it there while removing too so that I could unscrew the rear hanger assembly and it would hold while I removed the header section and then have the whole thing loose in my hands.

When you get the angle just right, the pipes pop right into the cylinder heads. (EDIT: And in my case, they held. The whole exhaust assembly from headers to muffler stayed put after it popped into place (hanging at the back as it was). I was then able to easily push the flanges up and into position through the studs, and carefully reattach and screw the acorn nuts down).

(I had the exhaust back on within minutes, literally).

Gary

 

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Just wanted to thank Loweriderbud for this thread.

I had installed the SC Project GP65 full system sometime last year and didn't think much about checking for exhaust leaks since I had plenty of experience installing aftermarket exhausts, nor experienced any exhaust leaks. <<---pride=not good!

I had read this thread weeks ago but for some reason this thread kept popping into mind yesterday. So I figured I'd check my exhaust for kicks and lo'behold...exhaust leaks on all my connections!!! o_O

So today I uninstalled and cleaned off the cheap exhaust liquid gasket that came with the exhaust (that was my fault right there...never use those!), and replaced it with Hi-temp exhaust gasket.

Gonna wait till it fully cures (24hrs) before testing for leaks.
 

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The more I think about it, make sure you're not too tight?

Are you confident in your torque wrench? I've found they are much like thermometers in their accuracy. Like most of us, I have the big ft/lb and the smaller in/lb wrenches. I used the in/lb for this and converted.

But the real takeaway when I think about my exhaust removal and reinstall, is just how loose those flange nuts seemed when I first removed them; it seemed barely beyond finger tight from the factory--if it was 15 ft/lbs, it was just that and no more. Thus my backing down from my cousin's recommendation and torquing them down to just a hair tighter than what I believe was there prior. I backed out and re-screwed a couple of times to be sure they weren't on too tight.

But my bike had just a few hundred miles on it when I did the work so I wasn't going to replace the gaskets. However, as Jim shows in the manual above, Honda does recommend changing out the gaskets each time you remove the pipes. If your bike has lots of miles, new gaskets it is.

Let us know what you find out. Good luck, Gary

A few pics of when I worked on my bike... I did remove the shield but left everything else connected when I removed and replaced the exhaust. I marked the bolts where the flange sat after removing the nuts, but didn't really have to check that upon reinstall... as I mention, the whole thing sort of "snapped" into place when it was lined up with a very definitive "feel" and movement. And the flanges were easily pushed up flush against the header.

...
How do you remove the old gasket? Do you need to apply some form of copper grease to the new gasket when reinstalling?
 

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They're just formed to the hole when they're tightened. Just poke around with a pick or screwdriver and pry them out. They're only about 1-2mm thick when used. Sometimes you find more than one in an older bike, because the last guy didn't notice there was one in there already. No grease needed.
 

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This comment is not going to help but may inform AT owners yet to fit crash bars. If you are about to fit bars to an AT, I would go with Heed or equivalent product that does not require the exhaust to be disturbed.
 

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They're just formed to the hole when they're tightened. Just poke around with a pick or screwdriver and pry them out. They're only about 1-2mm thick when used. Sometimes you find more than one in an older bike, because the last guy didn't notice there was one in there already. No grease needed.
Old gasket on the left, new gasket on the right. Important to replace these gaskets every time you loosen or remove header pipe.
I replaced these gaskets while installing Outback Motortek engine guards.
62572
 
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