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Cat Eliminator


bete

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Hi all; what is the general feeling when adding a cat eliminator to my r1100s, will I have to add something to richin the fuel mix? or will the o2 senser ajust?. thanks bete.

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"General feeling" is a pretty broad and a bit ambitious term, but there is certain contingency of us that promote the leaving catalytic converter in place; helping to save the air quality we all have to breath.

 

Removing it won't do anything to improve the bike anyway.

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Joe Frickin' Friday
Hi all; what is the general feeling when adding a cat eliminator to my r1100s, will I have to add something to richin the fuel mix? or will the o2 senser ajust?. thanks bete.

 

In the stock system your O2 sensor is upstream of the cat. As long as your new exhaust has a bung where you can install the stock O2 sensor, you shouldn't have to twiddle with anything else.

 

If there's no place to install the O2 sensor on the new exhaust, you'll need to replace the cat code plug (in the relay/fuse box) with a CO pot(entiometer), which can be used to manually adjust the mixture.

 

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Joe Frickin' Friday
I'm not sure it's worth your trouble as in my experience removal of the cat makes no preceptable difference in either power or mileage.

 

Hopefully the OP can elaborate, but my understanding is that a "cat eliminator" is an aftermarket exhaust system that does not include a cat. IOW, we're not talking about simply removing the cat from the stock exhaust. Don't know about performance benefits with a new exhaust (I suspect probably not much), but of course there's the acoustic and visual changes to be considered.

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Removing it won't do anything to improve the bike anyway.

 

Lighten the bike a bit and get rid of a large source of heat! (That's the main reasons I did it w/ Ztech 4000). Certainly does not make it go faster!

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Thanks all for the replys. Sorry to bring up bad feelings on the air quality and Ozone and all, my vain and childish motives were for a little nicer look and sound ( hopefully not loud ). As a side note, anytime I have done this in the past with other bikes I ended up going back to stock anyway, I guess just to much time on my hands to play. Thanks and sorry again. bete.

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I heard a nice sounding R at the ARC that I took. All he did was remove the muffler (to allow for a bigger side case), left the cat with only a little stub sticking out. Just as quiet as others at idle but a littel thoatier at speed.

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russell_bynum

 

Removing it won't do anything to improve the bike anyway.

 

Lighten the bike a bit and get rid of a large source of heat! (That's the main reasons I did it w/ Ztech 4000). Certainly does not make it go faster!

 

Note: Every one of my bikes has aftermarket exhaust, so what I'm about to say isn't coming from Ken's "stock exhausts only" position.

 

Yes, you're removing weight. But...it's just a few pounds removed from a very heavy bike. And it is weight that is down VERY low where it doesn't have nearly the impact on how heavy the bike feels. I'd be amazed if anyone could feel the weight reduction on a BMW.

 

Heat: So what? If you're making the argument that the catalytic converter's heat is bad for the oil in the transmission, you haven't looked at the numbers. If you're saying it just adds to the heat you feel when riding, I'm not convinced of that either. I certainly can't tell the difference on Lisa's R1100RS before/after.

 

Performance gain, as you said: none. Freeing up the exhaust will only add performance if the exhaust was a bottleneck. It isn't, so opening it up doesn't add performance. In some cases, people have reported that their oilhead ran worse after installation of an aftermarket exhaust. I suppose this is because BMW designed the stock exhaust specifically to take advantage of the air pulses and a generic aftermarket exhaust doesn't.

 

The only real reasons I've seen for putting an aftermarket exhaust on a BMW R11XX are looks and sound.

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Hopefully the OP can elaborate, but my understanding is that a "cat eliminator" is an aftermarket exhaust system that does not include a cat. IOW, we're not talking about simply removing the cat from the stock exhaust.

My understanding is that a cat eliminator pipe does just that and only eliminates the cat, retaining the stock exhaust. Or that would be the typical definition in the automotive world. I guess it really means whatever the speaker was thinking at the time. :grin:

 

It should be noted that a separate cat eliminator pipe can't be used on many BMW models as the cat and exhaust are built as a single unit. Either the entire exhaust system must be replaced or surgery performed to remove the cat element. And as noted neither is likely to have any performance impact on these bikes, just audible/visual.

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I gutted the cat. A little deeper high rpm sound, seat of the pants mid range boost if you have very thin pants on and I got rid of the heat, no problem with the O2 sensor. A good option unless of course you specifically want an aftermarket exhaust.

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