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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?

[GMR-PERFORMANCE]

Well you would reduced radiate heat on your leg , as the cat is still a cat and its entire purpose is to retain enough heat to burn any particulate's that are left in the ex gases. Without a doubt there could be better heat shielding on the head pipe, as well most import bikes use AIR to increase the cat temp and at idle and low speed its not in use , .. but that is not what HD does so it really does not matter.

[jrod_141]

Just to update: had the cat removed yesterday (no divider added).  Low RPM torque is noticeably better, throttle response is noticeably better, sound is obviously better.  no indicators of lean (pop on decel, hard starting when cold, spitting through the air intake).  So far, drive-ability is improved and seat-of-the-pants dyno says that a little torque was gained.  that's not to say that it wouldn't benefit from a tune, obviously it would.  however, $150 into it, i'm reasonably satisfied with the improvements.  Mileage was around 34-35 before, will advise once i get thru a tank to update. 

[GMR-PERFORMANCE]

I think I will do a test to dis prove all the internet myths about the de cat stock head pipe this fall.. I have a gutted one here and will run a stock bike untuned on the dyno with slip on mufflers and stock cat head pipe and then install the de catted pipe. I can tell you there is no increase in power at all.. as That much is simple but I feel the test would be better to show same bike back to back same day.. 
But I am sure I am pissing in the wind. But will be fun to have it on one sheet ..


Louder does not equal more power 

[jrod_141]

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..

Just had a lengthy conversation with Doc Weaver (docsperformancetuning.com).  Removing a cat should not make it rich, and GMR was correct about the cross-talk between the O2 sensors being the reason why the bike isn't running lean.  Essentially the O2 readings aren't good, and the ECM is compensating by adding fuel, but it's not ideal and shouldn't be left in this state for any length of time. 

[deldago]

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?

Getting rid of the cat reduces the felt heat on your leg big time!

[GMR-PERFORMANCE]

Correct there is a temp reduction when the cat is removed as a cat is built to be a heat sink and burn anything let in the ex system for EPA.. However done wrong and you create a tuning issue, some times it may take a while to get bad enough as the ECM will try to make changes based on incorrect 02 sensor readings.

Again buy a new head pipe with no cat tune the bike and do it correctly.

[deldago]

Definitely the best money I have ever spent on any of my toys was the Fulsac head pipe, baffles and tuner. I would do it again in a heartbeat! Between ditching the cat and getting the fuel ratio right it cooled things noticeably enough that my wife commented the first time she rode with me. I haven't done a dyno tune yet as I plan on adding some cams and compression this winter but there is a noticeable jump in power already with this combo.

[Fullsac Performance]

Take any late model Harley and do nothing other than remove the cat and at full throttle it will be lean off the chart. At steady cruise the closed loop portion of the fuel map will auto correct the AFR to about 14.9 - 1. The moment you crack the throttle the AFR will go to the north pole. Those are dyno proven facts as seen in a real dyno room.Nothing your going to learn in a classroom getting certified to do oil changes. Bottom line is you can "cruise" your Harley like this for thousand of miles and nothing bad will happen until you try pass another Harley that has been professionally tuned. Then you get smoked. You can even carry the certificate in the saddle bag, you still get smoked.

Ride safe

SG

[CVODON]

You missed your calling Steve, stand-up comedy probably less work!  Very good response to a totally unnecessary thread. How could ANYONE think increasing flow could create a rich condition?
Hopefully your skill level and response will settle this.

[East Coast]

No doubt you spent over $40,000 on your beautiful bike. Why go with the short cut now? Buy a head pipe which has been proven to reduce heat and provide better performance to help move the big bike a little quicker down the road. Then compliment the head pipe with a set of mufflers other than stock and tune it. The motor will run better than it does now and you'll like the seat of the pants feel even more.

 

[jrod_141]

No doubt you spent over $40,000 on your beautiful bike. Why go with the short cut now?

It was meant to be a hold-over until i get over to Doc's Performance Tuning and put on a DX head pipe and 2" fullsac cores and TTS tune.  Not trying to be cheap, just wanted a little extra oomph until i get it done right.  I had never heard of "O2 cross-talk" before, and i've been turning a wrench and tuning cars for a long time.  but i suppose that a cross-talk scenario is near impossible in a car, no matter what you do simply because of the way that exhaust is routed.  always something new to learn

[East Coast]

That sounds like a great plan! Good luck and shoot us an update after you see doc. 

[frydaddy96]

Have been doing a bunch of research on this de-catting business, lots of threads and heated discussion on other forums. Do a google search for 'hd cat gutting'  and 'de catting'.  Some fact like GMR-Performance has said and a lot of opinions. Here is my summary of these threads; If you just want to feel good about de-catting then go for it, about all you will get is less heat and more sound.  The cat is designed for good flow and isn't going to be restrictive unless you are over 110 motor size.  If you want REAL performance along with sound and less heat then spend the money on a designed, developed, and tested header. It looks like it comes to about $100 a horse if you go with the new header.

[nytryder]

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...

Got the same info from Doc here in Fl. I bought the Fullsac DX header in order to keep my original header in one piece. Just my preference. I've seen a lot of decatted CVO's that seem just fine, I just want to keep the original parts in one piece just in case.

[FLSTFI Dave]

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.

Bike comes way lean from the factory.  Removing the cat lets more air out of engine, which allows more air in.  More air with out more fuel, equals more lean... Not rocket science.  Are you leaving the air cleaner stock or adding a high flow?  If adding a high flow, it will be leaner.  Even if removing the cat and not adding an high flow air filter the bike will be lean, reason is STOCK it is very lean.

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.

And now we see the reason a HD certified Mechanic NEVER tunes my bikes. 

Doc in FL tunes my bikes for good reason.  He knows what he is talking about and what he is doing.

I can tell you my CVO King Built by me, tuned by doc blows by a bike with the same build by a local dealer and tuned by them.  In fact my 15 CVO Road Glide Ultra also tuned by doc runs neck and neck with this other bike built and tuned by a local dealer.

Take any late model Harley and do nothing other than remove the cat and at full throttle it will be lean off the chart. At steady cruise the closed loop portion of the fuel map will auto correct the AFR to about 14.9 - 1. The moment you crack the throttle the AFR will go to the north pole. Those are dyno proven facts as seen in a real dyno room.Nothing your going to learn in a classroom getting certified to do oil changes. Bottom line is you can "cruise" your Harley like this for thousand of miles and nothing bad will happen until you try pass another Harley that has been professionally tuned. Then you get smoked. You can even carry the certificate in the saddle bag, you still get smoked.

Ride safe

SG

Well said Steve and I agree.  That is why both my CVO bikes have your exhaust system, and why my wife 15 RGS does too.  Hers runs your base map for it also, runs like a top.