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Post collector back pressure?

Discussion in 'XJ Technical Chat' started by Calvert, Sep 24, 2018.

  1. Calvert

    Calvert New Member

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    I need to replace the mufflers/ silencers on my 1982 XJ650 Maxim. Headers are decent, collector is decent. My plan is to chop the mufflers off, weld on an adapter so I can eventually use an aftermarket slip on muffler. I can't afford new mufflers at the moment, many other things to do on the bike. I do have some turnout exhaust tips that I was thinking of using in the meantime. So my real question to the hardcore moto nerds is how this might affect exhaust flow? How much back pressure is provided by the mufflers if any? Basically, are there extreme negative consequences to altering the exhaust post collector?
     
  2. Craig B

    Craig B Active Member

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  3. Calvert

    Calvert New Member

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    Funny, I read that this morning and it almost left me with more questions than answers.
    I guess in my head, the majority, if not all of the scavenging occurs in the collector and header length. So I'm hypothesizing that the velocity of exhaust gases are at their maximum when exiting the collector at the point where they meet the mufflers.
    Or does the added length of the mufflers really add to the exit velocity? I believe the answer is yes, but I'm hoping it's not...
    Probably more carb jetting required either way.
     
  4. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Basically none
     
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  5. Colin 85 700

    Colin 85 700 Active Member

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    Most motorcycle shops should sell Emgo mufflers, they are cheap and look similar to OEM. Provided you have the stock collector, almost any pipe or muffler after that will work without majorly affecting back pressure.
     

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