De cat = MORE HEAT
Cruiser
Joined: Sep 2012
Posts: 185
Likes: 0
From: Mo.
This is a fundamental misunderstanding of how a fuel injected engine works. My closed-loop cruise area is at around 14.45 AFR (.981 Lambda), and it runs cool. That's because the VEs are corrected to produce that target AFR. The ECM will not do that on its own; the adaptive fueling can only compensate around 5% from the base map, and the base map is way lean. This is why it's so important to - via a dyno or street tuning - get the VE tables right. No inline resistor is going to do that.
Exhausts flowed just fine before catalytic converters were introduced, so don't think that you're hurting flow by removing the converter. Of course, you're not gaining much either, as the converter offers no restriction at stock or Stage 1 power levels.
Now with that said, you're not doing yourself any favors removing the converter from a stock pipe. By doing so, you're removing the media that keeps the exhaust flow somewhat separated from the two O2 sensors. Yes, you'll remove the heat from the converter, but your bike will never run right due to the commingling of the exhaust from the two cylinders in the huge open plenum you've just created.
There are no shortcuts, no matter how much anyone wishes there were.
Exhausts flowed just fine before catalytic converters were introduced, so don't think that you're hurting flow by removing the converter. Of course, you're not gaining much either, as the converter offers no restriction at stock or Stage 1 power levels.
Now with that said, you're not doing yourself any favors removing the converter from a stock pipe. By doing so, you're removing the media that keeps the exhaust flow somewhat separated from the two O2 sensors. Yes, you'll remove the heat from the converter, but your bike will never run right due to the commingling of the exhaust from the two cylinders in the huge open plenum you've just created.
There are no shortcuts, no matter how much anyone wishes there were.
Elite HDF Member
Joined: Oct 2010
Posts: 3,504
Likes: 12
From: DOWN SOUTH
ok so I gutted my head pipe....does not matter how, not gonna start that argument, but I got nice clean head pipe now on my 2011 sg 103. bike has Rinehart slip ons and that's it! have made a few short jaunts around town up to about 50 miles, great sound, but no diff in heat. so was able to get out for a few hundred mile ride, heat is worse than stock. so I figured maybe readjusting the pia heat shields, so I did and another 150 mile ride, still seems like excessive heat, what gives?? bike runs great, a slight de cell pop every now n then, over all happy just have a lot more heat than before. any one have any thoughts on what to do??
thanks
scottibe
thanks
scottibe
Ultimate HDF Member
Joined: Apr 2010
Posts: 5,308
Likes: 9
the xieds did the trick for me. tried the factory download from dealer on last bike...bike did run better, but the download takes it back to the e.p.a. mandated super lean ratio and does little for heat. you can find a set of used xieds for under a hundred bucks in the classifieds--the sellers say they worked fine but now they are doing cams, etc. and need more than the basic plug and play.
this time i gutted the cat and left the mufflers stock. the sound turned out pretty nice. added the xieds and every thing is hunky-dorey(to use a technical term).
this time i gutted the cat and left the mufflers stock. the sound turned out pretty nice. added the xieds and every thing is hunky-dorey(to use a technical term).
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
PS It is total myth that removing the cat will cause cross talk with the 02 sensors. It is a theory that in real life does not happen even though it is talked about on the HD internet forums. Unless one of the injectors is dirty or faulty there will not be a significant difference in their readings anyway. With or without the cat present in the collector tube ( not the head tube) there is no change in the flow. It would be the same odds for the 02's to cross talk with the cat and they do not.
If a person guts the cat,the o2 sensors are now reading the exhaust as being rich and therefore the ecm will in turn lean the fuel mixture.Why couldn't you just remove the o2 sensors from the pipe,not unplug them,just tuck them out of the way somewhere and plug the empty holes in the pipe.I would think in doing this the stock ecm would run the mixture as rich as it's able because the o2 sensors wouldn't be detecting anthing but clean air-?
Seasoned HDF Member
Joined: Oct 2012
Posts: 11,217
Likes: 3,045
From: St.Louis Mo.
If a person guts the cat,the o2 sensors are now reading the exhaust as being rich and therefore the ecm will in turn lean the fuel mixture.Why couldn't you just remove the o2 sensors from the pipe,not unplug them,just tuck them out of the way somewhere and plug the empty holes in the pipe.I would think in doing this the stock ecm would run the mixture as rich as it's able because the o2 sensors wouldn't be detecting anthing but clean air-?
Elite HDF Member
Joined: Jun 2011
Posts: 3,832
Likes: 127
From: Coastal Carolina
The guys that expect no heat are probably the same guys that expect a completely still bubble of air behind the fairing/windshield. If you want cool still air, get in a cage.
Thread Starter
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Advanced
Joined: Mar 2011
Posts: 70
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hey thanks guys for all the input, I didn't mean to start a great debate!! I know there is going to be heat, just like your hair is going to blow! however my concern was that now after de cat heat is worse, now having read every ones response I now have a better understanding of things, and have decided to try some xieds, sounds like a lot of good feedback with these. thanks again to all
scottibe
scottibe
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Grand HDF Member
Joined: Nov 2012
Posts: 3,751
Likes: 459
From: Here and now
My bottom line.
With stock hearder and mufflers my 2011 103 ran 445 degrees at the cat area of the header and the bike ran great. With slip on's the area ran 445 degrees and the bike ran great. With a de-catted head pipe the area ran 275 degrees and the bike still runs great. If it wasn't for the heat, I would not have de-catted but there is no way that area will run hotter without the cat. De-catting the pipe should change nothing but the heat.
With stock hearder and mufflers my 2011 103 ran 445 degrees at the cat area of the header and the bike ran great. With slip on's the area ran 445 degrees and the bike ran great. With a de-catted head pipe the area ran 275 degrees and the bike still runs great. If it wasn't for the heat, I would not have de-catted but there is no way that area will run hotter without the cat. De-catting the pipe should change nothing but the heat.
