Exhaust system “what if’s”
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Actually they're both. If you crawl up under your bike you'll see the actual exhaust pipes are small diameter stainless tubes. And that's what's coming out of the heads. But they're covered with a chrome shroud. And the same goes for the mufflers. You can see the unequal length stainless tubes under the bike that contribute to the unique syncopated CTX sound at low RPM that smooths out as you get rolling. :smiley-happy0034:
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And you are right. I was just trying not to get too technical about it. The chrome is a decorative shroud and covering over the parts you can see.
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Ok - to clear things up again. •IF• I do this, where I would be cutting the pipes would be just forward of the last curve where the twin pipes (top/bottom) are entering the converter. They are right on top of each other there - not even enough spacing to slide a credit card between them. Located directly behind the wedge-shaped chrome bling. I would •definitely• leave the kink in the front pipe to keep the lovely CTX pulse that Honda engineered into it. Had thought about affixing a 2-into-1 collector there, and just sending a single 1-1/4” or 1–1/2” pipe to the front of the “muffler”. Something like this: Parallel Merge Collectors Would definitely be easier, but think it would lose some of the 4-cylinder rumble.
* And I just realized the above opinion may be a misconception, as the stock system only sends 1 pipe out of each converter, and we still get a distinct V4 note.
* And I just realized the above opinion may be a misconception, as the stock system only sends 1 pipe out of each converter, and we still get a distinct V4 note.
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Well - have decided that I am not gonna hack up my exhaust. As much as I want to get a little better sound out of it, am really worried that modifying will end up in a reduction in torque. And, I don’t want to be without a bike while I try stuff out to see what works and what doesn’t. So, will be keeping an eye out for a used, wrecked-but-usable full set that I can cut on for my testing, and once I am happy with that, may mod mine. So - if anybody knows of a set of not-necessarily-pretty CTX1300 exhaust they can let go of for cheap, let me know. Am willing to be the test mule, as time and funds allow. Once have something to work off of, will get some audio of my stock (drilled) exhaust to compare to the modded.
Hate to have strung people along, but remember - this all started as a “what if”. And, after kicking a few things around with y’all, I do have a clearer plan of how I wanna go about it.
Hate to have strung people along, but remember - this all started as a “what if”. And, after kicking a few things around with y’all, I do have a clearer plan of how I wanna go about it.
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Still can’t get away from the fact that I ‘want’ this bike to have a little more “growl”.
Yesterday evening, got under it , took the shields and mufflers off it, and started looking and thinking again. Am thinking that the easiest way to do this will be to cut the twin pipes 1/4” or so before they enter the converters, install a pair of 2-into-1 merge collectors, and have the new single outlets connect to the stock muffler inlets. Would weld a bung for the O2 sensors into the middle of the collector. (This is similar to the stock setup, and no problems with the harness length.)
To do this, would probably be easiest to have the single pipes crisscross each other at the current converter location, since that’s the direction they’re pointed, anyway. The left 2 pipes would be fed to the right muffler, and the right 2 pipes to the left muffler. This would be the easiest way to get rid of the weight of the cats AND get a better exhaust tone, while still making it possible to go back to stock quite easily in the event that “it all goes horribly wrong”.
BTW - while having the mufflers off, tested it out for sound quality difference (through the cats) between mufflers and no mufflers. It’s definitely a little louder without, but not a whole lot. The cats muzzle it quite a bit. Mostly, the ting-y sound is gone. Rode it without the mufflers about 50 miles last night, just to make sure there were no driveability issues. Also, out of curiosity, I pulled the headpipes on the left side and fired it up for a couple seconds - just to see how much racket it would make with true open exhaust. Not near as loud as I figured. But I know it won’t sound anything like this when I delete the cats and go through the stock mufflers. Only way to know is to try it.
Yesterday evening, got under it , took the shields and mufflers off it, and started looking and thinking again. Am thinking that the easiest way to do this will be to cut the twin pipes 1/4” or so before they enter the converters, install a pair of 2-into-1 merge collectors, and have the new single outlets connect to the stock muffler inlets. Would weld a bung for the O2 sensors into the middle of the collector. (This is similar to the stock setup, and no problems with the harness length.)
To do this, would probably be easiest to have the single pipes crisscross each other at the current converter location, since that’s the direction they’re pointed, anyway. The left 2 pipes would be fed to the right muffler, and the right 2 pipes to the left muffler. This would be the easiest way to get rid of the weight of the cats AND get a better exhaust tone, while still making it possible to go back to stock quite easily in the event that “it all goes horribly wrong”.
BTW - while having the mufflers off, tested it out for sound quality difference (through the cats) between mufflers and no mufflers. It’s definitely a little louder without, but not a whole lot. The cats muzzle it quite a bit. Mostly, the ting-y sound is gone. Rode it without the mufflers about 50 miles last night, just to make sure there were no driveability issues. Also, out of curiosity, I pulled the headpipes on the left side and fired it up for a couple seconds - just to see how much racket it would make with true open exhaust. Not near as loud as I figured. But I know it won’t sound anything like this when I delete the cats and go through the stock mufflers. Only way to know is to try it.
Now you're talking - what a creative solution. I know from my experience fooling around with my CB1000R with a slip on that retains the catalytic converter and a 3/4 Yoshimura system that eliminates the cat that the cat does a lot of the sound dampening. Cool idea. :520:
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Well ... I’m looking at a pretty-good-shaped used right side header assembly that I just received. Has a scrape and small dent on lower side of front pipe. But I only have $55 invested - including shipping.
Have pretty much decided to keep the “muffler” 100% stock, and not insert the new single head pipe tube into the nose of it, as was my original plan. Thinking now that I will use a 2-into-1 merge collector, delete the cat conv, install an O2 sensor bung onto the collector, and have the new outlet insert into the current stock muffler inlet. (You know - that goofy-foot-looking 90* pipe on the back side of the “muffler”, entering at about the midpoint.) Have looked up parts for what I am wanting to do, but gonna wait until I can show it and explain it to a friend who is quite the master at welding, and see what he thinks.
What I have come up with is all from Cone Engineering (coneeng.com).
Looking at 304 stainless parts. The 2-into-1 collectors are #CL2-11315-SS , 18ga. The collector inlets are for 1.125” OD headpipes, and the single outlet is 1.5” OD. Will also buy a 2’ joint of 1.75” OD 16ga stainless tubing, #TU-ST16SS-1750 . This tubing is 1.620” ID, so thinking I can either crush this down a smidge or expand the collector a smidge to get them to slip fit rather snugly before welding. If I get angles right, should be able to get away with only one small bend per side. Want to get a ‘professional’ opinion first, as the collectors are $32.07 (x2), and the tubing is $27.95. Think this price includes ground shipping, but need to verify.
The other thing I am working on is a fixture or jig to hold the twin pipes in place once they are cut off the converter. Have already fashioned a flat plate and bolted the header flanges to it, so that end is good. Now just need to make something to ensure new outlet is at the correct angle, height, and plane as the old converter outlet, so the “mufflers” will still sit level.
If all goes as I have planned now, everything should ‘look’ 100% stock, but with a (hopefully!) throatier tone. And the computer should be a non-issue. O2 sensor will be at the collection point again, and I will make sure it is vertically in the exhaust stream about the same depth as stock.
Thinking I will get this first one made, get it installed, and see how it goes (sound- and computer-wise) before getting the other side. So ... stay tuned!
Have pretty much decided to keep the “muffler” 100% stock, and not insert the new single head pipe tube into the nose of it, as was my original plan. Thinking now that I will use a 2-into-1 merge collector, delete the cat conv, install an O2 sensor bung onto the collector, and have the new outlet insert into the current stock muffler inlet. (You know - that goofy-foot-looking 90* pipe on the back side of the “muffler”, entering at about the midpoint.) Have looked up parts for what I am wanting to do, but gonna wait until I can show it and explain it to a friend who is quite the master at welding, and see what he thinks.
What I have come up with is all from Cone Engineering (coneeng.com).
Looking at 304 stainless parts. The 2-into-1 collectors are #CL2-11315-SS , 18ga. The collector inlets are for 1.125” OD headpipes, and the single outlet is 1.5” OD. Will also buy a 2’ joint of 1.75” OD 16ga stainless tubing, #TU-ST16SS-1750 . This tubing is 1.620” ID, so thinking I can either crush this down a smidge or expand the collector a smidge to get them to slip fit rather snugly before welding. If I get angles right, should be able to get away with only one small bend per side. Want to get a ‘professional’ opinion first, as the collectors are $32.07 (x2), and the tubing is $27.95. Think this price includes ground shipping, but need to verify.
The other thing I am working on is a fixture or jig to hold the twin pipes in place once they are cut off the converter. Have already fashioned a flat plate and bolted the header flanges to it, so that end is good. Now just need to make something to ensure new outlet is at the correct angle, height, and plane as the old converter outlet, so the “mufflers” will still sit level.
If all goes as I have planned now, everything should ‘look’ 100% stock, but with a (hopefully!) throatier tone. And the computer should be a non-issue. O2 sensor will be at the collection point again, and I will make sure it is vertically in the exhaust stream about the same depth as stock.
Thinking I will get this first one made, get it installed, and see how it goes (sound- and computer-wise) before getting the other side. So ... stay tuned!
You're a wild man :520:
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Ok - got a little time to tinker with it today.
First off, my disclaimers. “This is for educational purposes only. For off-road use only. I do not suggest others make any modifications to their bikes.”
After a few days’ reflection, and spending a fair amount of time trying to fashion a suitable jig, I finally decided that it would be easier, and just as effective, to cut the converter open and ‘gut’ it. This would do away with the need for the 2-into-1 collectors and extra piping (which I received today but have not open). And I KNOW everything will line up!!
Used a cutting wheel on a full-sized hand grinder to cut the top off the converter (see pics). Used a combination of a reciprocating saw, a hammer and chisel, and drill bits to extract the honeycomb material. Had done this on my ‘87 Grand National and ‘94 TransAm, and they were a ceramic-type material. Not so this one. Is a metallic-type, and not as easy to remove. Anyway, after getting it out and eyeballing the innards, looks like will be much easier to cut the front cap on the converter for future attempts. I drew my cut area with a Sharpie on one pic.
Now, need to take the header to a welding shop and have them re-attach the top cover. Ended up with quite a few cuts trying to get it open. But nothing really bad. Next time (if needed) will be much smaller and much easier.
Next will need to get a sound clip of the before / after. For now, only gonna change the one side and see how it goes. Further updates in the (near?) future.
First off, my disclaimers. “This is for educational purposes only. For off-road use only. I do not suggest others make any modifications to their bikes.”
After a few days’ reflection, and spending a fair amount of time trying to fashion a suitable jig, I finally decided that it would be easier, and just as effective, to cut the converter open and ‘gut’ it. This would do away with the need for the 2-into-1 collectors and extra piping (which I received today but have not open). And I KNOW everything will line up!!
Used a cutting wheel on a full-sized hand grinder to cut the top off the converter (see pics). Used a combination of a reciprocating saw, a hammer and chisel, and drill bits to extract the honeycomb material. Had done this on my ‘87 Grand National and ‘94 TransAm, and they were a ceramic-type material. Not so this one. Is a metallic-type, and not as easy to remove. Anyway, after getting it out and eyeballing the innards, looks like will be much easier to cut the front cap on the converter for future attempts. I drew my cut area with a Sharpie on one pic.
Now, need to take the header to a welding shop and have them re-attach the top cover. Ended up with quite a few cuts trying to get it open. But nothing really bad. Next time (if needed) will be much smaller and much easier.
Next will need to get a sound clip of the before / after. For now, only gonna change the one side and see how it goes. Further updates in the (near?) future.
Attachments
Looking forward to hearing the results of your handiwork. Gotta love that good old American ingenuity. Others talk but you get it done. :520:
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Ok - got the header to a welding shop to put the converter housing back together. Came home, fired up a video of it with the original exhaust on it. Then pulled it apart, changed out the headers, reinstalled everything, hit ‘record’ again, fired the bike up and ...
(Drumroll, please)...
... Eh, it sounds pretty much the same. Just a tad louder, barely. Seriously bummed me out.
Am thinking it may get better if delete the cats altogether and have it pretty much straight into the (middle of the) mufflers, but I think that the biggest killer is that big open chamber ‘muffler’ with the sound having to bounce its way around before exiting. Pretty much the same thing is happening in the (now open) converter chamber.
Oh, well. $55 for the header, a couple hours of my time, and $45 for some welding. For that, I am (we are) more informed than I was yesterday. And I have a usable RH headpipe that is visibly in as good or better shape than mine. So, not a total loss. I’ve thrown away a lot more money than that on other ‘ideas’ and had absolutely nothing to show for it afterward!
(Drumroll, please)...
... Eh, it sounds pretty much the same. Just a tad louder, barely. Seriously bummed me out.
Am thinking it may get better if delete the cats altogether and have it pretty much straight into the (middle of the) mufflers, but I think that the biggest killer is that big open chamber ‘muffler’ with the sound having to bounce its way around before exiting. Pretty much the same thing is happening in the (now open) converter chamber.
Oh, well. $55 for the header, a couple hours of my time, and $45 for some welding. For that, I am (we are) more informed than I was yesterday. And I have a usable RH headpipe that is visibly in as good or better shape than mine. So, not a total loss. I’ve thrown away a lot more money than that on other ‘ideas’ and had absolutely nothing to show for it afterward!
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Got curious - pulled just the muffler off, fired it up just through the now-gutted converter. Much more along the lines of what I was looking for. Still kinda muted because of having to make all twists and turns and going through that converter housing. Guess it’s acting like an expansion chamber and cutting the sound out. Which is what the muffler is doing - too well! Am thinking the only way to get the sound I want and keep the looks stock will be to use the 2-into-1 collectors and route the exhaust into the front of the muffler, instead of the middle as is factory. But that’s gonna be for another time. Gotta lick my wounds a while...
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Put 30 miles on it this evening. No noticeable difference in performance. No oxygen sensor problems.
Noticed when I got home that the sound is a little louder than stock, but at about the same “tone”. Probably gonna ride it like this for awhile and decide my next move.
Noticed when I got home that the sound is a little louder than stock, but at about the same “tone”. Probably gonna ride it like this for awhile and decide my next move.
Regardless of the outcome you're a rock star for giving it a shot. I'm sure you've heard this but this is a sound clip of an ST1300 with Delkevic glass packs baffles removed.
This bike almost certainly still has the cats. I'm not sure this is the sound we're after either. Thanks for your hard work. Nothing ventured nothing gained.
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Well - after much consideration, I sent the merge collectors and assorted pipes back for credit. Was gonna be more involved (money- and time-wise) than I wanted to get into, trying to get everything lined up and fabbed up to make everything still look right. Still running the gutted converter on that one side. Have close to 1,000 miles on it, and no performance issues, no malfunction light.
Would I like it a little louder with a better tone? Heck yeah!!! But with the dual outlets drilled on each side, it’s alright. Besides, don’t have much disposable income with both kids attending Texas A&M, and us just having to drop $6K for a new a/c complete system for the house.
Would I like it a little louder with a better tone? Heck yeah!!! But with the dual outlets drilled on each side, it’s alright. Besides, don’t have much disposable income with both kids attending Texas A&M, and us just having to drop $6K for a new a/c complete system for the house.
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Just an FYI for those who may want to try to mod the exhaust in some way. I am STILL running that RH header pipe with the gutted-out cat converter. Been like this over a year and a half and 14,000+ miles, and have had no ‘check engine’ light, no driveability problems, and no noticeable change in performance or mileage.
I may revisit this again ... some day.
I may revisit this again ... some day.
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