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New mufflers=loss of MPG??

Discussion in 'Motorcycle Tech Talk' started by Rhots, Apr 6, 2010.

  1. Rhots

    Rhots New Member

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    Hi again, I wrote last week about whether or not to re-jet after putting on more open mufflers with an original equipment air cleaner. (thanks for the replies)

    Now..I seem to have lost about 2.4 MPG. Does this make sense to anyone?
    If I go to a more open air cleaner it wouldn't be "choked" as much, but then it might be too lean and need bigger jets. So I would lose MPG anyway.

    Your thoughts and expertise are appreciated!!!!

    Rick


    RIDE SAFE!!
    Rhots, Apr 6, 2010
    #1
  3. 59panhead

    59panhead New Member

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    LOL Well anytime a guy goes with new pipes and there loud there always rapping em up at ever stop light Hey LQQK @ me and my noise makers ! Its a guy thing!

    anyway have you done a plug test from 40,60, and 75-80 mph read the plugs ! are they running rich, lean or perfect ? What exhaust did you go to? ALL Harley motors are to lean Stock....so its most likely way 2 lean now!
    and do a mpg test with out rapping on the right grip for a day and do the math up the jet size and retune the bike....lean is mean but lean means heat and no gas and more air kills a motors performance let alone the pistons
    59panhead, Apr 6, 2010
    #2
  4. Rhots

    Rhots New Member

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    LOL I get what you mean, but I am an old fart. My bike almost never goes over 3k RPM and I usually coast to a stop in neutral. I take off slow and stop slow.
    Basically, like I tell my boys, "I drive it like it's gonna break". So anyway, yea I'll keep checking it.
    Thanks,
    Rick
    Rhots, Apr 6, 2010
    #3
  5. hotroadking

    hotroadking Super Moderator Staff Member

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    How many times have you checked mileage, it needs to be done over several rides, not one or two as the variables on a ride are too great, hills, wind, rain, type or throttle management (twisting the throttle a bit more to hear the new pipes etc)

    If you didn't change anything but the pipes I doubt they are the cause of the MPG change you experienced.
    hotroadking, Apr 6, 2010
    #4
  6. Art_NJr

    Art_NJr New Member

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    I was fixin' to say much the same as "59panhead" regarding riding the bike differently after an exhaust change - bet you use more throttle than you used to! And every time you twist that throttle, you make the accelerator pump shoot raw fuel down the carb throat.

    Just a muffler change (usually) does nothing to the mixture - if you get a free-flowing air-cleaner too, then yes, you will need to go up on the jet size - how much will depend on the particular bike. Think of the engine as an air pump - you can't get any more out of it than it'll take in.
    Art_NJr, Apr 6, 2010
    #5
  7. FLHTbiker

    FLHTbiker Moderator Staff Member

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    If anything I would think it could be running a bit leaner.
    FLHTbiker, Apr 6, 2010
    #6
  8. 59panhead

    59panhead New Member

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    Im almost 60 and ride my 59 pan like I just stole it....but doing a plug check is easy and you know what the motor needs more gas or more air
    59panhead, Apr 6, 2010
    #7

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