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Discussion Starter #1 (Edited)
Hey all,

I have a 2016 model w/ the Graves full titanium system. I installed this when I got the bike in 2016, and shortly after installed smog block-off plates, disabled AIS in FlashTune, etc. It's also been given a fuel map created for this bike+exhaust that has led to flawless performance until now.

The issue is that just this year I've begun noticing some popping again on harder decel and when upshifting at high RPMs, which prompted me to check the exhaust. As it turns out, there are carbon buildups at both 1 of the 3 header pipes into the midpipe, and an even worse one where the can connects to the midpipe. NO ISSUES at the header connections to the engine. I confirmed this by feeling air coming out of those joints with my hand. Due to the fact that I want to use FTECU ActiveTune to tune as I ride, this leak would be detrimental to that performing correctly as the O2 sensor readings could be wrong. I need absolutel perfectly sealed exhaust flow.

So... I would love some wisdom on how to best approach fixing this.
- My first thought is to try taking the whole system off (headers, midpipe, can), and re-fitting/installing it hoping that there were just misalignments causing the leaks. I doubt this will really work though, since even if that's the case, the titanium might be out of perfect shape/fit by now.
- I have read about people using Permatex Ultra Copper or other RTV silicone gasket makers to seal these kinds of joints — can somebody please confirm that this is both effective and SAFE? It does say on the package that it's safe for sensors, but I'm no expert.

I remember being a bit surprised there was no sealants when installing the exhaust originally, but reading leads me to believe it's atypical for the exhaust pipes to not fit perfectly snug/airtight. Obviously I've either messed up alignment a tad when installing it, or fitment isn't always perfect; intuition would lead me to believe a sealer would be good with or without an already perfect fit, esp when using a closed loop tuning product like ActiveTune.

EDIT: I went ahead and disassembled and reassembled the system using Ultra Copper. Now I wait 24 hours and check for leaks!
 

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I don't understand how you come to the conclusion you have exhaust leaks...

Are your assuming you must have a leak because of the backfire? The AIS is not the only reason for the back fire... Lots of cam overlap and factory tune also contribute to it. It would be less with the AIS disabled but not totally gone..

But yes using exhaust sealant on the joins is fine - less is more. A few heat cycles and it will seal hard.

Sent from my SM-G930F using Tapatalk
 

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Discussion Starter #3 (Edited)
Thank you for the response mt09downunder!

I don't understand how you come to the conclusion you have exhaust leaks...
It started as a suspicion, then a confirmation. I confirmed this by feeling air coming out of those joints with my hand. It is very noticeably blowing air out of 1 of the 3 header->midpipe joints and at the can joint.
I double-verified this with a bee smoker and watched it get displaced by the air flow.

Are your assuming you must have a leak because of the backfire? The AIS is not the only reason for the back fire... Lots of cam overlap and factory tune also contribute to it. It would be less with the AIS disabled but not totally gone..
My AIS is disabled and blocked off. I already know this can't be a cause – no fresh air injection = no inner-pipe combustion pops. It's not fuel tuning either, as I went from a perfectly tuned(map created just for this bike/setup) running system to one that is now backfiring – that's what indicated an exhaust leak inspection needed done to me. To a lesser degree, having a leak is equivalently detrimental to a tuning setup as having AIS disabled, as an improper O2 sensor reading due to the leaks could be screwing up the ECU closed loop trying to maintain a static AFR.

But yes using exhaust sealant on the joins is fine - less is more. A few heat cycles and it will seal hard.
Awesome! This is what I was ultimately seeking confirmation on. I think that thinking about the physics logically, a sealant, perfect fit or not, can only serve to help in guaranteeing a leak-proof system. Just wanted to be sure that it's going to be safe for application with a big Bosch 4.9 wideband sensor for ActiveTune :)


Curiously, will that RTV sealant cure up very permanently? I hope I never have to, but if I'd ever need to take the system back apart again, would that then be a large task of breaking some adhesion?
 

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I would take it to a qualified professional to review before trying anything, you would not want to ruin your beautiful titanium exhaust. I have a good understanding of both FT ECU and power commander products. What most people don't understand about autotune is not a can in fact map worse than having it dyno because you are not writing optimally at each RPM level. I think in this situation it's worth having a pro look at it.

Hope this helps!
 

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Thank you for the response mt09downunder!



It started as a suspicion, then a confirmation. I confirmed this by feeling air coming out of those joints with my hand. It is very noticeably blowing air out of 1 of the 3 header->midpipe joints and at the can joint.
I double-verified this with a bee smoker and watched it get displaced by the air flow.



My AIS is disabled and blocked off. I already know this can't be a cause – no fresh air injection = no inner-pipe combustion pops. It's not fuel tuning either, as I went from a perfectly tuned(map created just for this bike/setup) running system to one that is now backfiring – that's what indicated an exhaust leak inspection needed done to me. To a lesser degree, having a leak is equivalently detrimental to a tuning setup as having AIS disabled, as an improper O2 sensor reading due to the leaks could be screwing up the ECU closed loop trying to maintain a static AFR.



Awesome! This is what I was ultimately seeking confirmation on. I think that thinking about the physics logically, a sealant, perfect fit or not, can only serve to help in guaranteeing a leak-proof system. Just wanted to be sure that it's going to be safe for application with a big Bosch 4.9 wideband sensor for ActiveTune :)


Curiously, will that RTV sealant cure up very permanently? I hope I never have to, but if I'd ever need to take the system back apart again, would that then be a large task of breaking some adhesion?
No it's not a glue or anything it just forms a hard barrier once dried properly. It is similar to a ceramic or hard clay when dry. You don't use much just a thin layer. Wipe off any excess once you put it together. That will seal any small gaps.

I'm surprised they didn't include any with the exhaust.. doesn't matter the quality of the exhaust you are always going to have an amount of play.

Anyway I would try that first

Sent from my SM-G930F using Tapatalk
 

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Discussion Starter #6 (Edited)
I would take it to a qualified professional to review before trying anything, you would not want to ruin your beautiful titanium exhaust. I have a good understanding of both FT ECU and power commander products. What most people don't understand about autotune is not a can in fact map worse than having it dyno because you are not writing optimally at each RPM level. I think in this situation it's worth having a pro look at it.

Hope this helps!
Thank you for the advice! When all is said and done, I DO intend to get some Dyno time to at the very least inspect the quality/accuracy of the tune after a couple hundred miles, and if truly necessary (if the product didn't do a great job on the street), I can hopefully have them run it on the Dyno while ActiveTune is enabled.

Re: bad autotune maps, I'm definitely aware of that fact — but am also aware of the deficiencies that certain (inertial) Dynos have that make them even less than ideal for tuning "cruise range" than street riding. This is advice I got from tuners like VCycleNut directly. They've all warned me about using an esp. slow piggyback system like DynoJet AutoTune that is too slow/doesn't know if ECU is on MAP or TPS maps, etc and will result in crap tunes for at least cruise range. I guess that "Eddie Current" Dynos are better for this kind of thing? It's important to note the distinction in products here — I intend to use "FTECU ActiveTune" not "DynoJet AutoTune".

A tuner and FTECU have also told me that ActiveTune's PID loop frequency is at least 100x faster than DynoJet AutoTune's and since it has scope to the ECU's internal state, can make much more intelligent, real-time adjustments to set AFRs down low and better account for things like reversion. I trust that you might have expertise here as you say too with their products, and I wonder if you feel the same about ActiveTune as you do AutoTune given these improvements, or if there is more to the story that you may know, please share as I am here to learn from you guys :D

As far as ruining the exhaust, it's just not a possibility with something like this. The only risk at all would be to an O2 sensor potentially picking up uncured/low-viscosity solutions, unlike this more rigid and explicitly sensor-safe RTV silicone.

No it's not a glue or anything it just forms a hard barrier once dried properly. It is similar to a ceramic or hard clay when dry. You don't use much just a thin layer. Wipe off any excess once you put it together. That will seal any small gaps.

I'm surprised they didn't include any with the exhaust.. doesn't matter the quality of the exhaust you are always going to have an amount of play.

Anyway I would try that first

Sent from my SM-G930F using Tapatalk
I've heard of other aftermarket exhausts coming with at least some anti-sieze which may or may not partially help with sealing, but I agree — if this works out as I expect (re-fitted with Ultra Copper, now waiting on it to cure) then I see absolutely no reason why I won't do this on every aftermarket exhaust install from this point forward. You can only get so far because as you said yourself, metal slip fits, no matter how tight or well machined, will always have some play due to all the variables: tolerances, minor stress from mounting, constant vibrations and heat cycles, etc. Thank you again!
 

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I have an XSR900 but I also have Graves Full Ti along with a FTECU Tune (Graves) and an activetune module.

The FTECU tune would pop on decel and also die sometimes. After switcing to the graves tune, it has been all good.
 

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Discussion Starter #8
I have an XSR900 but I also have Graves Full Ti along with a FTECU Tune (Graves) and an activetune module.

The FTECU tune would pop on decel and also die sometimes. After switcing to the graves tune, it has been all good.
So you're using ActiveTune to trim the Graves flash's fueling now? Or are you saying that you removed ActiveTune and kept the static Graves flash? Just curious.
 
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