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Thread: How to - Catalytic convertor removal

  1. #1
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    How to - Catalytic convertor removal

    The catalytic converter has been a part of stock exhaust systems since around 2009 ish and can be found in either the mufflers on the earlier models or the header system on later bikes. Eliminating the cat in the mufflers is easy - just bin them and buy decent mufflers. Those located in the header system are a little more tricky but the result is worth it. I remove them regularly so I thought others might be interested in doing the same. It's not a difficult job and the benefits are - much less heat retained in the exhaust system, a little more power and a little more of that sound that we all love. I've never dyno'd a bike before and after but you can feel a slight increase. Its definitely worth doing even just for the reduction in heat.

    This is the header system with the cat area opened up. I use a slitting disc for this. The converter is now exposed and can be removed.

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    Its pretty tough stuff but it does come out. I've used a few tools over the years but have now settled on a pneumatic hammer with a chisel attachment. You can get it out with a manual hammer and chisel then a scraper to get the remainder off of the inner surface, but it's hard work.

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    Here's what the exhaust looks like once the cat is out.

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    Take the section that you cut out and the pipe to be welded.

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    There it is - job done!

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    Something else I do at the same time is to weld open the active exhaust valve. I break the spring then remove it completely, hold the valve wide open and weld it in position.

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    There you have it - a free flowing exhaust system with the cat gone and the valve wide open presenting much less resistance to flow.

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  2. #2
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    Re: How to - Catalytic convertor removal

    I removed the 02 sensors on my Triumph unplug and bin them I purchased 2 plugs for the i'm presuming the ECU end so do you have to do the same with the De Catted Harley pipes

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    Re: How to - Catalytic convertor removal

    Quote Originally Posted by Army View Post
    I removed the 02 sensors on my Triumph unplug and bin them I purchased 2 plugs for the i'm presuming the ECU end so do you have to do the same with the De Catted Harley pipes
    I'm not following - the O2 sensors stay in place.

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    Re: How to - Catalytic convertor removal

    Hi Alex if you leave them plugged in does it not send a error signal or does it just read as normal, I suppose when I replaced the headers on my triumph I had no option but to unplug and add the plugs at the electronic end so I suppose if you put a set of de catted headers without the 02 sensors then you will need to add the blanks at the electronic end

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    Re: How to - Catalytic convertor removal

    My FLHTCU still has the cat but oxygen sensors removed and electrical connections capped with a red ended plug.
    Urrell , Rep Region 23


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    Re: How to - Catalytic convertor removal

    Quote Originally Posted by Army View Post
    Hi Alex if you leave them plugged in does it not send a error signal or does it just read as normal, I suppose when I replaced the headers on my triumph I had no option but to unplug and add the plugs at the electronic end so I suppose if you put a set of de catted headers without the 02 sensors then you will need to add the blanks at the electronic end
    There's no connection between the function of the sensors at the cat. Because the exhaust has to be removed to eliminate the cat, the sensors have to be unplugged from their sockets which are usually behind the right side panel on Tourers or under the seat on Dyna/Softails. Once the cat is removed and the pipe back in place the sensors can be reconnected which is required for the closed loop area of the tune to function. There's no error code generated as nothing has changed. If you replace the headers with a pair that have no sensor ports then you can either weld them in or use the plug in eliminators. This is not required when removing the cat and refitting the pipe.

    Quote Originally Posted by Urrell View Post
    My FLHTCU still has the cat but oxygen sensors removed and electrical connections capped with a red ended plug.
    The closed loop function is eliminated in yours then Nic - has it been flashed with a Power Vision?

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    Re: How to - Catalytic convertor removal

    thats what my thinking was Alex I presumed the closed loop function would remain if the original pipes were refitted. i'm of the understanding that a set of headers without the CAT will produce less heat so a bike running cooler and producing a slight increase in power if it has been Dyno tuned

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  8. #8
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    Re: How to - Catalytic convertor removal

    I went the full header replacement route but, out of interest, wondered if it's feasible to remove the exhaust valve, cut off the butterfly and reseal the valve port with the remnants. That way there be no obstruction (pressure drop) to impede exhaust flow?

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