Killing the Cat
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Intermediate
Joined: Apr 2006
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Killing the Cat
This could go in the "exhaust" section, I guess, but it's pretty specific to baggers:
My '06 SG just passed 2k miles, and with the Dobeck tuner/fueler is giving me everything I could want (otherwise stock - I like it that way). Only problem is the damn crossover heat issue, which we've all been over a thousand times. Bikes are stupid-lean from the moco, you get a tuner or sert or duals or some kind of tweak to fatten them up. Helps some with the heat. But as of '06, the right-side stock muffler has a catalytic converter in it (check p48 of the owner's manual, or read the underside of the muffler, where it says "catalyst"). Anyone remember when they started putting cats on cars, and people who parked them on dry grass were starting fires? These things get very hot, and I have to assume that without the cat the heat factor would be diminished a little more.
So I asked my dealer if he had any pre-'06 right-side pipes that people had taken off & left there when they bought replacements, and he gave me one that looks brand new. No cat in it. I'm going to install it in the next day or so.
My question is, does anyone know if the cat-free muffler will change the mix substantially? Any other issues you know about in changing this out? I would assume that eliminating the cat would affect the airflow to some degree. BTW, if you're thinking about this, remember that the right side slip-on IS different from the left; it has a dimple that lets it clear the rear axle.
Thanks in advance
RR
My '06 SG just passed 2k miles, and with the Dobeck tuner/fueler is giving me everything I could want (otherwise stock - I like it that way). Only problem is the damn crossover heat issue, which we've all been over a thousand times. Bikes are stupid-lean from the moco, you get a tuner or sert or duals or some kind of tweak to fatten them up. Helps some with the heat. But as of '06, the right-side stock muffler has a catalytic converter in it (check p48 of the owner's manual, or read the underside of the muffler, where it says "catalyst"). Anyone remember when they started putting cats on cars, and people who parked them on dry grass were starting fires? These things get very hot, and I have to assume that without the cat the heat factor would be diminished a little more.
So I asked my dealer if he had any pre-'06 right-side pipes that people had taken off & left there when they bought replacements, and he gave me one that looks brand new. No cat in it. I'm going to install it in the next day or so.
My question is, does anyone know if the cat-free muffler will change the mix substantially? Any other issues you know about in changing this out? I would assume that eliminating the cat would affect the airflow to some degree. BTW, if you're thinking about this, remember that the right side slip-on IS different from the left; it has a dimple that lets it clear the rear axle.
Thanks in advance
RR
Cruiser
Joined: Jun 2006
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From:
RE: Killing the Cat
My '06 Ultra did not have a cat, it was still way hot. The fix for me was true duals...
I would think that removing the cat would throw off the air/fuel mix a great deal becuase the sensor is no longer feeding info to the ECM.
I would think that removing the cat would throw off the air/fuel mix a great deal becuase the sensor is no longer feeding info to the ECM.
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RE: Killing the Cat
It is. Guess that's why nobody ever takes off the stock stuff!
Just kidding.
Thanks for the suggestions on the duals; I know that's the eventual answer to the heat issue, but for several reasons I'm going to keep things basically stock for a while. My thinking with the '05 muffler is that losing the cat would surely have some effect.
I'd guess that the airflow would increase to some degree, and that I'd have to add a little fuel to compensate. I was looking for a word from someone who's done this or knows for sure what the effect would be.
Thanks
RR
Just kidding.
Thanks for the suggestions on the duals; I know that's the eventual answer to the heat issue, but for several reasons I'm going to keep things basically stock for a while. My thinking with the '05 muffler is that losing the cat would surely have some effect.
I'd guess that the airflow would increase to some degree, and that I'd have to add a little fuel to compensate. I was looking for a word from someone who's done this or knows for sure what the effect would be.
Thanks
RR
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Tourer
Joined: Dec 2005
Posts: 260
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From: Freehold, NJ
RE: Killing the Cat
I replaced the stock mufflers on my 06 SG with B&E Superflows, which are just modified stock 06 mufflers with the cat drilled out and a glass packed baffle welded into each. I ran for at least 1,000 miles with no other mods and the bike ran fine. No leaner than it was from the factory (which isn't saying much) and the plugs always looked good.
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Advanced
Joined: Aug 2006
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From:
RE: Killing the Cat
I don't know much about bikes yeet, but the o2 sensor that is by the cats on cars is only to show if the cats are efficient. They do not affect the A/F mixture.
The 02 sensors on the exhaust manifolds or headers on a car are the ones that the PCM uses to adjust A/F mixtures.
I am not happy that I have to look at $500 to buy a tuner for something that I shouldn't have to tune when all I have is the stage 1 pipes and air induction. From all I have read, the download from HD is not good and it requires tuning. It seems to me that even stock requires tuning.
I don't want to start a rant, but if the tuning is that bad on a mostly stock bike, then tuning for removing the cat should be irrlevant so it needs to be tuned anyway.
The 02 sensors on the exhaust manifolds or headers on a car are the ones that the PCM uses to adjust A/F mixtures.
I am not happy that I have to look at $500 to buy a tuner for something that I shouldn't have to tune when all I have is the stage 1 pipes and air induction. From all I have read, the download from HD is not good and it requires tuning. It seems to me that even stock requires tuning.
I don't want to start a rant, but if the tuning is that bad on a mostly stock bike, then tuning for removing the cat should be irrlevant so it needs to be tuned anyway.
Road Warrior
Joined: Jul 2006
Posts: 1,532
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From: Rochester N.Y.
RE: Killing the Cat
Hey Boof , the elimination of the converter in the right hand muffler has a very small effect on flow and sound. Don't ask me how I might know that...
The crossover pipe will always be pretty hot because it's closer to your body parts.
In order for a catalytic converter to properly work , it must be very hot.
In the automotive world , the cat is brought up to very high temp very quickly in order to do good things as fast as possible for the environment.
Removing the catalyst "will" reduce heat because it's job is to produce heat and finalize the combustion process.
o2 sensors before a conveter are used for mixture control , 02 sensors behind the converter establish how good a job it did to the ECM.
A properly running converter "can run as high" as 1700 degrees F (internal converter temp).
Converters used to start grass fires alot in cars , that is why they have heat shields top and bottom "usually" nowdays.
Just a couple of thoughts...
Mick
The crossover pipe will always be pretty hot because it's closer to your body parts.
In order for a catalytic converter to properly work , it must be very hot.
In the automotive world , the cat is brought up to very high temp very quickly in order to do good things as fast as possible for the environment.
Removing the catalyst "will" reduce heat because it's job is to produce heat and finalize the combustion process.
o2 sensors before a conveter are used for mixture control , 02 sensors behind the converter establish how good a job it did to the ECM.
A properly running converter "can run as high" as 1700 degrees F (internal converter temp).
Converters used to start grass fires alot in cars , that is why they have heat shields top and bottom "usually" nowdays.
Just a couple of thoughts...
Mick