spit back

Discussion in 'Motorized Bicycle General Discussion' started by MitchP, May 3, 2013.

  1. MitchP

    MitchP New Member

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    My bike's been spitting fuel. half of it might be my shoddy fuel line but here it goes. There's dirty gas on the carb, the line and the spot where the clutch screws into the top of the case. I'd like to keep it running, any suggestions?
     
  2. 2door

    2door Moderator
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    It would help us to know what engine and carburetor you have but assuming you have a 2 stroke in-frame here's some info.

    Some blow back out of the carburetor throat is nomal with a 2 stroke, piston ported engine but it sounds like you have a fuel leak. The fuel line that comes with the kits is notorious for hardening and cracking quickly. The barb fitting where the fuel line attaches to the carb can also be loose. The bowl gasket might be the culprit too.

    Clean everything off well and start watching for where the fuel is coming from. A float that is too high will also cause fuel to seep. Always use the fuel petcock. Shut it off when the bike is parked.

    Tom
     
  3. MitchP

    MitchP New Member

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    It's an NT carb (the one that's a step below the RT, correct?) and besides being a little oily, the air filter is clean, no dirty crud in it. I really should get better line, it's the black stuff, seemed pretty good. There is also certifiably unburnt fuel (suggesting a leak) pooling up on the top. It's not dire but everyday it's back, mucking up my white frame!
     
  4. 2door

    2door Moderator
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    Oily residue doesn't necessarily mean it is "unburnt". 2 stroke exhaust is naturally oily. By "pooling up on top" what do you mean. Pooling where precisely? If "top" is the cylinder head it could be leaking at the spark plug gasket or the cylinder head gasket or stud nuts.

    The exhaust manifold gaskets that come in the kits aren't the best. You'd be wise to replace it with a good quality gasket material and checking that the gasket surface on the exhaust flange is flat and sealing well.

    If you mean pooling under the carburetor, then do as I suggested above and look for the leak source. Probably carburetor bowl gasket or fuel line, float level too high, stuck float valve or a petcock that doesn't shut off correctly. Some builders have found the plastic donut float leaks and doesn't float. That will allow the fuel level in the carb to overflow. Check the float that it doesn't have any fuel in it.

    Tom
     
  5. MitchP

    MitchP New Member

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    Ok. It seems to start at the petcock. Does motorbicycling.com have a favorite brand of fuel line?
     
  6. nightcruiser

    nightcruiser New Member

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    I've been very happy with the fuel valve I got at SickBikeParts.com. You need to install an inline fuel filter since there isn't a filter built into it like the valve that comes with the kits, but you're much better off that way....
    After you replace the valve take the two screws out of the old one and take it apart so you don't have to wonder why it had to be replaced! LOL
     
  7. MitchP

    MitchP New Member

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    I know it's POS. SBP sells good stuff, and I need a hotter plug anyways.
     
  8. nightcruiser

    nightcruiser New Member

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    They've got a nice sintered bronze fuel filter over there too...
     
  9. CTripps

    CTripps Active Member

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    Time for a trip to your local NAPA (or similiar) store. A few feet of 1/4" ID fuel line, a handful of clamps, and you're good to go.

    (If you haven't replaced your plug wire and boot already, add those to the list while you're there)
     

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