added an exhaust, mpg got worse?

Discussion in 'Parallel Universe' started by leungevity, Sep 21, 2017.

  1. leungevity

    leungevity Adventurer

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    So I know it doesn't make much sense, but what are the chances that adding an exhaust (cat back) to a 2011 f650gs twin would hurt the MPG?

    i know it might be possible i'm revving harder, but i don't think that's the case. could the exhaust alone make the bike run more rich or some other thing that hurts fuel economy?

    thanks!
    Mike
    #1
  2. Dyrden

    Dyrden Been here awhile

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    More free flowing usually means less torque down low and means more fuel(since there is more air). Less torque might mean you're reving it higher to find the power as well.
    #2
  3. KILR0Y

    KILR0Y Was here...

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    New tone sounds cool, right? You're prolly rolling on the throttle more to hear the coolio sounds, and hence burning more fossil fuel!

    BTW, not trying to sound like a prick but you're still getting near 50mpg's I'm guessing, so roll that sucka open and enjoy it! I'm pretty sure you didn't buy the exhaust simply for economy sake.

    More importantly, what brand did you buy and how does it sound? Inquiring minds want to know...

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    #3
    Rudolph F700GS likes this.
  4. Indy Unlimited

    Indy Unlimited Long timer

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    Might be your 02 sensor on the exhaust
    #4
  5. Tigershark48

    Tigershark48 Been here awhile

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    This is a common result on posts regarding aftermarket exhausts. The Af-Xied control module also decreases mileage as do performance enhancing ecu tunes. Most mods from the factory setup do this as BMW tends to maximize gas mileage.

    As posted in this thread by Kilroy, dropping a couple of mpg on a high mileage bike isn't a bad trade off for improved sound and performance. Enjoy!
    #5
  6. leungevity

    leungevity Adventurer

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    so i bought the exhaust from another inmate... it's the danmoto conical gp exhaust. the sound is loud, and it tends to drone a bit. at start up it's a a higher pitch bark, more than a low grumble, from there it just gets more obnoxious. it's A LOT lighter than stock... is a sound video thing something that would be wanted for this particular exhaust?

    i was thinking maybe it was an O2 sensor as well, but the cat back has no sensor...

    i am still getting in the 50's, but my overall average mpg went from 59 to 56 almost immediately. I definitely have been more aggressive on the throttle on occasion, but i don't think enough to drop the MPG that much.
    #6
  7. Tigershark48

    Tigershark48 Been here awhile

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    Danmotos are more like an ornament on a header pipe :hair
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  8. leungevity

    leungevity Adventurer

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    lol, i can tell you that it certainly doesn't make me miss my ducati any less.
    #8
  9. Indy Unlimited

    Indy Unlimited Long timer

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    I am running Remus headers without a cat and the stock muffler and with AF-Xied set at 6 and I am getting 55 mpg for most of my riding. It can go as low as 50 mpg and as good as 60 mpg but I usually get 55 mpg. My bike has 80,000 plus miles on her.
    #9
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  10. morfic

    morfic Adventurer

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    Has your mileage stabilized (or better asked returned) after the initial "this sound is new, let me play with that"?
    56 is still above my 54 avg I get before and after installing an aftermarket exhaust.


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    #10
  11. leungevity

    leungevity Adventurer

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    the mpg has been all over the place, with it sometimes being as good as 63 i think and then dropping down to 56 again yesterday. if i could figure out how to make the bike make the popping noises on demand, i probably would have kept the exhaust on the bike, just for the entertainment value of that, but since it did it whenever it wanted to and i couldn't recreate it on demand, i put the stock exhaust back on again.
    #11