"leaking" from fuel tank air vent hose - bit of weird stuff going on

Discussion in '6th Generation 2002-2013' started by irishrOy, May 23, 2018.

  1. irishrOy

    irishrOy New Member

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    Hey guys!
    I just need another opinion than mine, I feel :D

    Due to not having a garage my VFR is sitting in the yard.
    The VFR is covered with a thick motorcycle cover but the sun is directly hitting the VFR from like 12 to 16 o'clock. During that time the cover and of course all will heat up.

    Now I can't help but notice how there's a small "puddle" or so forming under the bike. It's not a realy puddle, but just a darker area where drops land. This only really happened when the bike is standing in the sun/being heated up.

    The VFR didn't have any real leaks so far. No oil, a few drops of coolant due to the previous owner not having attached the coolant-reserve-tank properly.
    And just a few droplets of water forming on the exhaust belly since it's quite misty here from time to time.


    I've already taken a closer look, and yes, it's the most front hose, the fuel tank air vent.
    When I touch it with my finger, the hose is a bit "wet" and the air is shimmering beneath it (vapors and all that, I guess).

    Left is the bike's front in this picture:
    [​IMG]

    What's your opinion on that?
    Is this a problem, is this normal? :D
    (The Viffer is my first "complicated" motorcycle, before that I only had an '94 Suzuki VX 800 and a '97 Shadow 750 Ace, so I'm not used to so much technical stuff and hoses going around).
     
  2. RllwJoe

    RllwJoe Insider

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    Has the tank been full while sitting under the cover?
     
  3. Terry Smith

    Terry Smith Member

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    That vent hose is the only vent point for the fuel tank, so if it heats up in the sun the vapours will definitely be driven out through the hose. Unless the tank is very full I would not have thought you'd get any liquid however.
     
  4. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    Probably nothing to worry about assuming you had recently filled the tank with fuel and then left it parked in full sun for several hours.

    When heated petrol will expand (quite a lot), so that pipe provides a way to avoid potentially dangerous pressure build up inside the fuel tank by safely discharging some excess fuel onto the road. The pipe is carefully positioned to minimise the risk of the bike catching fire or petrol damage to the paintwork on the bike.

    You should however worry if it also occurs with the tank partly filled.

    SkiMad
     
  5. irishrOy

    irishrOy New Member

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    The "fuel meter" was ~1-2 bars shy of "completely full".

    So I filled the tank up, bot not to the brim (or at least it didn't look so extremely full. But maybe I topped it off quite nicely, too, which would explain the overflow)

    That's what I thought as well. :D

    Okydoke, got it. I plan on not filling it up anymore anytime soon, just 50-75% to keep some room for "expansion"
    I wanted to test it today with only about 2-3 bars of the "fuelmeter" in, but it's raining right now and a bit cold.. :/

    But did anyone of you experience a "discharge" like that after the bike has been standing in the sun, or is this a rare thing to happen?
     
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