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[jrod_141]

My harley mechanic, whom i 1) trust implicitly based upon past experience, and 2) rarely use only because i'd rather do it myself, was talking to me about exhaust.  He told me that in his experience, removing the cat and re-coring or replacing the mufflers ends up running just a little bit rich, and doesn't necessarily need to be re-tuned.  Now, having tuned enough vehicles personally, i am inclined to agree with this statement. 

Reason I ask is because he'll pull the head pipe, cut open and remove the cat, weld back together and put it back on the bike for $150 (which is a great deal, as far as i'm concerned).  I intend to re-core the SE mufflers with FullSac 2.25" cores and the packing screens that they offer, and have Tom remove the cat from the stock head pipe. 

For you guys out there that have done this, can anyone else confirm your results?

[ultrafxr]

This is not first hand but a friend used a core drill to remove the cat from his '11 RUSE leaving the stock mufflers in place.  I don't know how thorough a job he was able to do of getting all the cat material removed.  He did not tune and reports that he can tell no problem.  He wanted a little bit louder exhaust and said removing the cat gave him that.

I have heard and read that removing the cat exposes both O2 sensors to the same stream of exhaust gas and can set up cross talk between the sensors.  With the cat in place the sensors are isolated. 

[jrod_141]

never really considered that, but i'm a little skeptical only because the O2 sensors are upstream from the cat.  i'm not sure how removing the cat would cause erroneous fuel readings, but then again i'm not an expert in fluid dynamics either.  strange and mystical things happen in exhaust pipes, some of which i just don't get...

[FLSTFI Dave]

My harley mechanic, whom i 1) trust implicitly based upon past experience, and 2) rarely use only because i'd rather do it myself, was talking to me about exhaust.  He told me that in his experience, removing the cat and re-coring or replacing the mufflers ends up running just a little bit rich, and doesn't necessarily need to be re-tuned. Now, having tuned enough vehicles personally, i am inclined to agree with this statement. 

Reason I ask is because he'll pull the head pipe, cut open and remove the cat, weld back together and put it back on the bike for $150 (which is a great deal, as far as i'm concerned).  I intend to re-core the SE mufflers with FullSac 2.25" cores and the packing screens that they offer, and have Tom remove the cat from the stock head pipe. 

For you guys out there that have done this, can anyone else confirm your results?

I will dis-agree with what he told you.  Removing the cat should increase flow of Exhaust.  If so, that lets more air in the engine for next combustion cycle.  Which means, if it changes the air flow removing the cat, you will be lean.

These bikes come from the factory lean, so this would make it even leaner.  This is not good.

I have removed the cat on my 09, Had it tuned as it was Lean.  Used Fullsac head pipe on the 12, with no cat, lean again and had it tuned, same with my 15.

[jrod_141]

makes sense to me.  thank you sir!

[Para Bellum]

These bikes come from the factory lean, so this would make it even leaner.  This is not good.

X2.  It will be leaner if you remove the catalytic converter.

[aa8wl]

Hello all. I am a newbie here and I have a question. We own a 2013 Tri Glide and I just installed Screaming Eagle pre EPA mufflers and a K&N a/c and I bought a TTS unit to tune this setup. Does anyone have a good starting map as I cannot find anything matching the setup I have. I have read and re-read till I am blue in the face and cannot quite understand the whole process yet but I am still working on it. I am sure I am just not understanding the instructions well enough yet. I am hoping to find a map close to get me by until I can begin Etuning the bike.

Thanks in advance
Sam and Teri
Utica, MI

[jrod_141]

Just an update:  spoke with another friend of mine (HD dealer mechanic for 30+ years).  He said that more than likely it will be a little rich if you simply remove the cat.  he said do it and ride it and see how it feels.  gonna have the cats cut out next tuesday, will report back on how she does.

[hawgzilla]

I would like to hear your friends explanation as to how an engine gets richer when you remove a restriction from the exhaust flow.  I've never seen that happen--- but I've only been dyno tuning for 23 years.  I don't have nearly the experience of a 30 year HD mechanic.

[jrod_141]

I would like to hear your friends explanation as to how an engine gets richer when you remove a restriction from the exhaust flow.  I've never seen that happen--- but I've only been dyno tuning for 23 years.  I don't have nearly the experience of a 30 year HD mechanic.

i'm not arguing that point, i'm with you.  it flies in the face of everything i have ever learned about tuning, and i'm not a pro, just a shadetree.  but this is two certified HD mechanics that have told me the same thing... i'll let you know what happens.  going over there at 1100 on tuesday to have him cut the cats out.  if it's lean, i'll know it pretty quick.  will post back as soon as i have news.

[HOGMIKE]

Hello all. I am a newbie here and I have a question. We own a 2013 Tri Glide and I just installed Screaming Eagle pre EPA mufflers and a K&N a/c and I bought a TTS unit to tune this setup. Does anyone have a good starting map as I cannot find anything matching the setup I have. I have read and re-read till I am blue in the face and cannot quite understand the whole process yet but I am still working on it. I am sure I am just not understanding the instructions well enough yet. I am hoping to find a map close to get me by until I can begin Etuning the bike.

Thanks in advance
Sam and Teri
Utica, MI

After you run the "software updater", check the various TTS maps for something close to what you have, that will be a good starting point.
I have done 2 2010 tri-glides and the owners are very happy, no changes to their bikes since 2010!
Where you bought your TTS may also have a map with your particular combo, you may want to ask.

Steve Cole would also be a good source to contact. He should be able to walk you through the setup, but not really that difficult, just follow the instructions and take your time.
JMHO
Good luck.

 

[RGlideKid]

I will dis-agree with what he told you.  Removing the cat should increase flow of Exhaust.  If so, that lets more air in the engine for next combustion cycle.  Which means, if it changes the air flow removing the cat, you will be lean.

These bikes come from the factory lean, so this would make it even leaner.  This is not good.

I have removed the cat on my 09, Had it tuned as it was Lean.  Used Fullsac head pipe on the 12, with no cat, lean again and had it tuned, same with my 15.

I will have to agree with Dave here.  My experience and research has pretty much backed up this theory, and it only makes sense when you stop to think about it.

[mjb765]

I will have to agree with Dave here.  My experience and research has pretty much backed up this theory, and it only makes sense when you stop to think about it.

Have to agree with this as well. Losing the cat will make it run leaner, not richer.

[GMR-PERFORMANCE]

Well removal of the cat 99% of the times is going to be done wrong. The stock 02 sensor placement is too close to the now empty chamber. The front and rear sensors must not getting readings from the other cylinder. This is called cross talk so it may be lean it may be rich or both in different areas on the map.. Now if you where to remove the cat ( flow is not a issue btw) you need to have a divider in there and make sure that they are not cross talking.. This is a old topic and tuners have long  seen the poor results from this gutting the cat deal. 

I would suggest that you buy a new head pipe tune the bike.. I know you have people tell you it runs fine. Ok lets put that to the test and lets load one of those bikes on a dyno and lets take some 02 readings and see what is really going on..

I tune stock bikes with cats on a very regular basis and tuned they will run cooler there is no performance gain to be had as we have run the non cat to cat back to back and they make the same power ( with stock cams)

I have seen a few that where done correctly, but its more work and by the time you add up everything a basic head pipe can be bought.. Buy the fulsac + correct tuner tune the bike and forget about it.. ( low cost great bang for the buck).  Good luck

[banana]

If there is no power gain with stock cams (cat vs decat) why bother changing out the header pipe? Why not just buy a tuner & dyno the bike?