Fuel balancing line

Discussion in 'Airheads' started by droadguy, Sep 11, 2017.

  1. droadguy

    droadguy Adventurer

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    Hi! The tank on my fuel tank only had one petcock and I've decided to go to a two petcock tank. I have seem some people talk about installing a "fuel balancing line" between the two lines from the petcocks and am wondering what the purpose of that is? And, if it's necessary? Thanks for the help!
    #1
  2. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Without the balance tube, the possibility exists of one carb running out of fuel first. It's a no brainer, really. I never did get BMWs reasoning for building the tanks with only one petcock...
    #2
  3. motu

    motu Loose Pre Unit

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    Plus you get two reserves.
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  4. disston

    disston ShadeTreeExpert

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    What year and model bike do you have? I'm not sure which bikes had only one petcock. You may be limited in which tanks with two petcocks will fit that model.

    Two petcocks are an advantage for several reasons. Sort of like NASA, it's redundant. Provides a cushion of fuel supply.

    Unfortunately the idea of two reserves is misleading. You can flip the petcocks anyway you want when you are running out of gas. You will still get the same number of miles.
    #4
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  5. Warin

    Warin Retired

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    Yes the total range is the same. If you run only on one petcock with the other turned off you might get more warning as the off side might have more fuel in it. Once you run out on one side, including its reserve you then get to use the other side, so there are successive warnings. It increases the number of reminders before you start walking/hitching.

    ---------------------
    Coming from a one petcock bike - just keep the same fuel tube that transferred fuel to the other side, easy. You will need a tee piece and added fuel line.
    #5
  6. motu

    motu Loose Pre Unit

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    In my case it's 2 different size reserves...I know how far I can get on each reserve, and plan accordingly. I don't see the point in turning both taps to reserve, you just need the one....then the other....and then start getting worried.
    #6
  7. boxerboy81

    boxerboy81 Stay Horizontal

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    Yes, two warning systems really. 1. Time to seriously think about refilling. 2. Time to get refill is imminent.
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  8. ME 109

    ME 109 Long timer

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    I have three reserves. When the left main runs out, flip the right main, when it runs out flip the left reserve, when it runs out flip the right reserve. It's handy for knowing where the fuel's at, if not recording miles. I don't often record miles because I'm having fun riding may bike and forget, and not all miles are the same.
    I've run out of fuel about four times in twenty five years, and rolled down to a fuel bowser with a stalled engine bout the same amount of times.
    #8
  9. Box'a'bits

    Box'a'bits In need of repair

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    I got caught out when doing a road trip to pick up new to me bike. Ran out of gas a couple of times. Firstly because the balance pipe wasn't there. Then it turned out that the straws had been removed on one side, so no reserve there.
    #9
  10. 190e

    190e Long timer

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    R45/R65's have one petcock and if that's what he's got, other two petcock tanks will not easily fit if at all.
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  11. droadguy

    droadguy Adventurer

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    Thanks for all the replies, they really help!

    I currently have an R80ST and am going to fit a /7 tank with two petcocks on it, see thread about those struggles here. If you have any pointers on that please let me know :)
    #11
  12. OdyBandit

    OdyBandit Been here awhile

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    R65 has one Petcock on left side. If you run out on reserve you can lay the bike on its left side and move the bit of fuel remaining in the right side to the left.
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  13. 190e

    190e Long timer

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    I've done that more than a few times although in my old age I find it much easier to lift the tank and tip it over to the left. There must be a good litre as a 2nd reserve on the right side.
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  14. CafeDude

    CafeDude Ride to eat.....

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    You can always braze a threaded bung on the other side of whatever tank you have to add another petcock.
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  15. Beemerboff

    Beemerboff Long timer

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    Later tanks are thinner on the right side so you get more reserve if you run on the RHS first, then switch to the left.
    If you have in line filters you can remove the straws from the reserve position - with the quality of fuel these days removing and cleaning the taps and flushing the tank should be a yearly service item anyway - one trip up country can leave me with half an inch of sludge in the bottom of the tank and blocked filters!
    #15
  16. droadguy

    droadguy Adventurer

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    Do you guys know what I could use for fuel lines that would look a little better than the standard rubber hoses that come on these bikes? I'm not looking to spend a fortune on them but I would like for them to look a little bit nicer.
    #16
  17. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    You have the stock braided lines? BMW sells a solid rubber fuel line used on fuel injected carbs in the same size.
    #17
  18. Beemerboff

    Beemerboff Long timer

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    Get the stuff with - J30 R12 - printed on it , and it will stand up to crap gas.
    The braided stuff is just junk and a waste of time and money, and couldn't be legally fitted to a new vehicle today.
    #18
  19. disston

    disston ShadeTreeExpert

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    Nothing looks better on an Airhead than the braided fuel line. Almost anything else will work or last better but I miss the braided fuel line if it's not there.
    #19
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  20. droadguy

    droadguy Adventurer

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    disston where can I get braided fuel lines?
    #20