Catalytic converters. Can I remove it?

Discussion in 'GS Boxers' started by strsout, Jan 17, 2007.

  1. strsout

    strsout Banned Camp

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    Is there a problem removing the catalytic converter on a 2003 GS?
    Have you done it?
    What is involved?
    I ear that if you remove it, you don't have to worry about lead/unlead gas.
    Also I would guess about 5 pounds less on the bike.

    Thank you
    #1
  2. Oro D

    Oro D Been here awhile

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    #2
  3. strsout

    strsout Banned Camp

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    A lot of disagreement there :) :)
    I guess I got one good info about Sebring Y-Pipe. Looks like that would be the way to go.

    Now, for those who removed the catalytic converter:
    1) is there any increase in noise?
    2) is there any increase in consumption?

    Those are two things I don't want, so I'm not sure if it's a good idea or not to remove the catalytic.
    #3
  4. NZGSer

    NZGSer Momentum is my friend

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    Hi,

    A catalytic converter is just a device that treats the exhaust before it leaves the engine and removes a lot of the pollutants now being attributed to global warming etc. etc. (different debate so let's not go there). Legislation in Europe is primarily responsible for all BMW (and other Euro brand) motorcycles being equipped at manufacture with catalytic converters these days.

    Your bike is equipped with a three-way catalytic converter. "Three-way" refers to the three regulated emissions it helps to reduce -- carbon monoxide, VOCs and NOx molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required (they are very expensive).
    <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2.

    <o:p></o:p>

    The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. <o:p></o:p>

    The third stage is a control system that monitors the exhaust stream, and uses this information to control the fuel injection system. There is an oxygen sensor mounted upstream of the catalytic converter, meaning it is closer to the engine than the converter is. This sensor tells the engine computer how much oxygen is in the exhaust. The engine computer can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the engine computer to make sure that the engine is running at close to the stoichiometric point, and also to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO.<o:p></o:p>
    <o:p></o:p>
    So, if the environment is not your primary concern, unbolt your exhaust and part with it - the catalytic converter is inside. The amount of noise you get will depend on the pipe your replace the original with, most manufacturers of aftermarket pipes give you a dB rating – usually around 88 or thereabouts with some for of restictor so as to keep you legal on the road.

    Fuel consumption should not change a lot as the oxygen sensor mounted further forward on the header system is still using information to control the fuel injection system and the amount you burn.

    Hope that helps.
    Garry
    #4
  5. WetRoots

    WetRoots ........ just gnarly

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    ........... shit !!!! I thought I knew how those things worked, and I did know ...... I just forgot about their importance. I thought I would bin mine on the next bike, but I might think about it a bit more. I mean the environment is important ...... thats where we live and ride. It is, however, an argument to keep the cat and can the can. Air pollution is more tangible than noise pollution ........ maybe rip it out anyway, and be more ethical in other areas. I will start by leaving my cat on, until I start looking for ponies. Thanks for reminding me of the wonders of catalytic converters.[​IMG]
    #5
  6. MRHAPPY

    MRHAPPY GSIN

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    WHAT THE HELL IS WRONG WITH A NOISY BOXER????THEY SOUND BEUTIFULLLLLL,,,just ask the sport bikes that are usually looking at the back of my carbon akrapovic:freaky
    #6
  7. markgsnw

    markgsnw WTF?

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    consider leaving the cat and replacing the can...I've done this, I've got better sound and a bit more power, plus the benefits of the cat.
    #7
  8. strsout

    strsout Banned Camp

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    It does help. A long explanation on what it does.
    Environment is a concern for me, yes (I still separating trash in 3 different bins), but I will be using this bike to a long trip overseas and some people alert me about the fact that unleaded gas maybe not available there, and that it could cause a problem.
    I'm not planning to replace the pipe, unless there is a related reason for it (I don't want more noise, neiter more power from the pipe).

    Thank you again :)
    #8
  9. Idatoe

    Idatoe Been here awhile

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    I have an '03. Axe the Cat. You'll love it. No heater, big weight loss. I tried to replace just the cat with a Staintune collector box but it does not work with any muffler but Satintune. The OEM and a Remus Canister both hit the saddle bag. The Staintune muffler does not hit the bag but it does direct the exhaust higher up into the license plate and turn signal creating a heat issue.
    I reccommend Remus Y-pipe and muffler. I actually switch from the Remus can to the Staintune when I use the left side saddlebag, but run the Remus most of the time because of the heat issue.
    #9
  10. strsout

    strsout Banned Camp

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    Someone mention that I could jut open the OEM pipes and remove the catalyc from inside?
    is that true?
    If I don't want change the pipe, would that be a quickly and cheap solution?
    How difficult would be to remove the cat from that OEM pipes w/o damaging the whole thing?

    Ramus pipe is much lighter then the OEM pipe? and how about noise? and price?

    Thank you
    #10
  11. RedUly

    RedUly Esse Quam Videri

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    Leaded gas will destroy your O2 sensor which is needed for the fuel injection system.
    #11
  12. strsout

    strsout Banned Camp

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    So how one will ride in countries where only leaded gas is available?

    Is then better to keep the cat and take chances?
    #12
  13. space

    space a.k.a. Jake

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    Wow. Great info, Garry. Thanks!

    Do you know how much NO and unburnt hydrocarbons typically come out of these bikes? I'm trying to rationalize the cat from a global warming perspective. Is the fraction of NO or NO2 molecules in the exhaust even close to the fraction of CO2? If it's many orders of magnitude lower (which would be my guess), then I don't see the point of the cat. Even if they do have a larger global warming potential per molecule than CO2. (aah, the neat info you can find on wiki!)
    #13
  14. NZGSer

    NZGSer Momentum is my friend

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    The main by-products of combustion are:<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    <o:p></o:p>
    Nitrogen gas (N2): Our atmosphere is 78 percent nitrogen gas, and most of this passes right through your engine.<o:p></o:p>
    <o:p></o:p>
    Carbon Dioxide (CO2): A harmless, odourless gas composed of carbon and oxygen. It is also a greenhouse gas that contributes to global warming.<o:p></o:p>
    <o:p></o:p>
    Water vapour (H2O): Another by-product of combustion. The hydrogen in the fuel bonds with the oxygen in the air. <o:p></o:p>
    <o:p></o:p>
    These three emissions are mostly harmless, although carbon dioxide emissions are believed to contribute to global warming. However since the combustion process is never perfect, other more harmful emissions are produced in the process.<o:p></o:p>
    <o:p></o:p>
    The three main regulated emissions, and also the ones that catalytic converters are designed to reduce, are:<o:p></o:p>
    <o:p></o:p>


    Carbon monoxide (CO): A colourless, odourless gas. It is poisonous and extremely dangerous in confined areas, building up slowly to toxic levels without warning if adequate ventilation is not available.<o:p></o:p>

    <o:p></o:p>
    Hydrocarbons or volatile organic compounds (VOCs): Any chemical compound made up of hydrogen and carbon.<o:p></o:p>
    <o:p></o:p>
    Oxides of nitrogen (NOx): Chemical compounds of nitrogen, they combine with hydrocarbons to produce smog.<o:p></o:p>
    <o:p></o:p>
    In order to reduce emissions, modern engines carefully control the amount of fuel they burn. They try to keep the air-to-fuel ratio very close to what is called the stoichiometric point, which is the calculated ideal ratio of air to fuel.<o:p></o:p>
    <o:p></o:p>
    Theoretically, at this ratio, all of the fuel will be burned using all of the oxygen in the air. For petrol engines the stoichiometric ratio is about 14.7:1. This means that for every litre of petrol, 14.7 litres of air will be burned. As engine and driving conditions change, this ratio changes as well. Sometimes it will run richer or leaner than the ideal 14.7:1.

    You can work it out if you have loads of spare time but the short answer is that if alll of the fuel is burned using all of the available oxygen in the air/fule mix then your bike's catalytic converter does a very good job of removing most of the regulated emissions, BMW claim up to 95% reduction in total emmisons with the use of a converter against an engine without one.

    Whew!!

    Cheers
    Garry
    #14
  15. markgsnw

    markgsnw WTF?

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    leaded gas destroys the converter chemistry, I don't think it has an effect on the O2 sensor.
    #15
  16. markgsnw

    markgsnw WTF?

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    leaded gas will destroy the cat. If you're planning on riding in a country with leaded fuel, you'll want to remove the cat beforehand.
    #16
  17. strsout

    strsout Banned Camp

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    So it's that kind of situation:
    you leave it there, the gas will destroy the cat.
    you remove it, the gas will destroy the ox sensor...
    bummer.
    #17
  18. space

    space a.k.a. Jake

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    Destroys = temporarily renders the cat ineffective? Or destroys = your cat will never remove NOx and whatnot again?
    #18
  19. TexBiker

    TexBiker Been here awhile

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    I've never heard of leaded gas harming the 02 sensor on any vehicle. I know of several GS's that ingested hundreds of gallons of leaded gas with no damage to the 02 sensor.
    #19
  20. WetRoots

    WetRoots ........ just gnarly

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    .... an interesting thread. Here in Australia where unleaded fuel is now the predominant fuel. There is a stronger argument for keeping the "cat" alive. I have always thought on my "about to be delivered" 12 GS /A that at the first opportunity I would put in a Staintune or Akrapovic or Remus full system. But that cat has merrit. There was and is a need for it, it is a clever and effective piece of enginerring, it has been designed and incorporated into the GS and comes standard, and we have all paid for it. So what if it weighs a few KG's and saps about ???? HP ......... its not a very strong counter argument. LONG LIVE THE CAT !!!!! :freaky .....


    This is my firmly held belief for this moment in time only.
    #20