Gas Tank Caps, , , , Hmmmmmm

Discussion in 'Motorized Bicycle General Discussion' started by fredgold52, Mar 24, 2012.

  1. fredgold52

    fredgold52 New Member

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    Does anyone here have a gas tank cap that doesn't leak? If so, how in the world did you make it that way, 'cause I can't believe for a second it came from the factory that way.

    I painted ny original gas tank, with paint that was not fuel proof. After a while, I got tired of seeing my paint job drip on to the street, So, I bought a larger chrome tank. I love the new tank but even with two gaskets in it the new cap leaks.

    So waddayouthink? Is there any hope for this?
     
  2. rustycase

    rustycase Gutter Rider

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    Yup.

    These lil' thangs get GREAT fuel mileage.

    Don't top off the tank!

    Otherwise, you will need to get a fuel-proof clear spray paint that is compatible with the base coat you are using.

    Best
    rc
     
  3. Mike B

    Mike B New Member

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    Nope. They're crap.

    Never ever fill it up so far that the gas touches the bottom of the cap or it won't just leak, it will gush.
     
  4. Ibedayank

    Ibedayank New Member

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    use a better tank.. not one made in china or don't fill the tank up all the way
     
  5. The_Aleman

    The_Aleman New Member

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    Double-up the gasket, make your own cap vent. That's how I battled all my leaky kit tank caps.
     
  6. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    I simply made my own tank, and made my own gas cap. (I love how I worked in the word "simply". I was kidding: there wasn't nuthin' simple about it.) I took a garden hose fitting and matching cap, drilled a rivet hole in the center of the cap and a vent hole about 1/4 inch away. On the inside of the cap I used a 1/16 inch thick piece of Nitril rubber riveted in the middle. It acts as a kind of flapper valve. I also have a Nitril rubber o-ring seated in the inside of the cap so that, when I tighten down the cap, it seats against the fitting. My cap don't leak a drop, but it vents really well and the Nitril I used is just thick and stiff enough that a pressure build-up can push past.
     
  7. mapbike

    mapbike Active Member

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    I always make sure that there is about 1 1/2'' between fuel level and the bottom of gas cap, as it has been said already, never completely fill china kit tank or you can get a serious fuel link, I think we have all learned that lesson at least once.

    Best solution is to use a different tank, when I have the time I plan to make tanks for all my bikes, but until then the china tanks are just fine as long as they aren't over filled.
    (^)

    Peace, Map
     
  8. lowracer

    lowracer New Member

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    My little Tanaka PF3300 doesnt leak at all & breathes too...
    Wish I knew how the Japanese do it
    -Lowracer-
     
  9. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    It's called "quality control".
     
  10. thegnu

    thegnu New Member

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    nuff said lol
     
  11. fredgold52

    fredgold52 New Member

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    Yeah, Japan pretty much has the quality thing nailed. South Korea is catching on. Mainland China just not there yet. Although I have to say there's some very good work in my HS 4 popper.

    I guess I got my answer. Don't fill it near the top. OK, I can do that. 'Cause I got this real purdy chrome 3.5 L tank. Looks good, holds lots of gas even if not full. I'll live with it.
     
  12. lowracer

    lowracer New Member

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    Come to think of it, I never had any issues with a leaking cap on my Lifan 2.5 hp 98cc engine (china made)...
    -Lowracer-
     
  13. Drewd

    Drewd New Member

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    I called poor design and for the life of me I don't understand why any HT manufacturer can't figure out how to improve on the design. Oh, never mind, the Chinese are waiting to copy a U.S. design that fixes their problem.
     
  14. 2door

    2door Moderator
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    Don't fill the tank and use fuel proof paint. Carry a few paper towles with you when you ride and wipe away the seepage. (discard the used paper towles in a government approved container so the tree huggers don't come after you.) :)

    The leakage is from the vent. Not a lot you can do about it. Double gaskets won't help. The tank has to be vented to the atmosphere and gasoline will find its way out of any opening, which the vent is. Deal with it. It's just a fact of HT/kit part ownership.

    Tom
     
  15. happycheapskate

    happycheapskate New Member

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    Holy smokes, you are not kidding! I thought I was going to die in a fireball the one day I filled my happytime up to capacity! I got back on the street and took off, no problem. At about 20mph and speeding up, fuel started SPRAYING all over my chest and face! I killed the motor and pulled over to a yard, ready to stop drop and roll, but nothing happened, so I just hosed off before it started chemically burning me up.

    I suppose you can dry out your cap, solder fill the vent hole, and dry out your tank (seriously! don't play) and drill for a grommet and weedeater line, and run that line just barely inside the tank, and down to the bottom of the frame. Else you can make it 1" -3" long and add a check-ball vent cap to it from mower shop. That should do it!
    PS you will still not be able to fill it 100%.

    It's possible you could modify the cap, but it would probably be more sure thing to seal it and vent the tank. The cap has a spring and stuff in it, not sure how hard it would be to drill through.

    [​IMG] http://blaisracingservices.com/images/uploads/KTM Parts/KTM_Fuel_Tank_Vent.jpg
    KTM gas tank cap vent dirtbike

     
    #15 happycheapskate, Apr 22, 2012
    Last edited: Apr 22, 2012

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