Strange issue

Discussion in 'Motorized Bicycle General Discussion' started by tomcfitz, Oct 22, 2013.

  1. tomcfitz

    tomcfitz New Member

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    Yikes. let me first start out by saying that i'm in a computer lab, and i think this is the wost keyboard I've ever used. It only registers about 7/10 key presses.


    I have just finished a cheapo china girl/wal-mart build, and after riding it around 15 miles yesterday (Class and back), I made it around 7 today when the engine quit working correctly.

    It will start just fine, and if i get it up to a speed, it holds the speed, but only barely, no acceleration. As soon as I disengage the clutch, the engine dies.

    I was working fine until then, and I made no adjustments to the eng:-||ine or bicycle before it quit. Any ideas?
     
  2. crassius

    crassius Well-Known Member

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    first, adjust your idle screw to keep it running. then ride it a lot to get the motor broken in a bit
     
  3. tomcfitz

    tomcfitz New Member

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    I'll try that, but I'm fairly convinced that the idle screw isn't the problem, as i doesn't run correctly even above idle, and it was idling fine, even a little high, and the screw as not been adjusted at all since.
     
  4. FMB42

    FMB42 New Member

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    Check for loose cylinder/head nuts. Make sure that the carb is both pushed all the way onto the manifold and tight. Check the spark plug for looseness and fouling.

    And when you can, give us some more info such as; pre-mix oil brand/type and ratio, spark plug brand/type, etc.
     
  5. mapbike

    mapbike Active Member

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    Ditto.... sounds like it could be an air leak at a gasket or carb.

    Map
     
  6. tomcfitz

    tomcfitz New Member

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    Okay, the headbolts were fine, but I retorqued them anyway, the spark plug seems fine, but I'll replace it tomorrow (I have a spare sitting around).


    The carb is very tight, I don't see any leaks there, but I tightened it again.

    Still not working though. Anything else I should try?
     
  7. 2door

    2door Moderator
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    This might sound odd but is your throttle working?
    When you twist the throttle does it lift the slide in the carburetor? If I'm understanding your problem, the engine will start but doesn't pull the bike and stalls when you release the clutch?
    Sounds like a throttle cable issue to me.

    Tom
     
  8. tomcfitz

    tomcfitz New Member

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    No, it stops running when the clutch is disengaged. The throttle cable works fine.
     
  9. crassius

    crassius Well-Known Member

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    some engines are so rich before they are broken in that the idle screw won't go in far enough to keep it running - dropping the needle down to the leanest notch will get the idle mixture into a range that the idle screw can handle
     
  10. FMB42

    FMB42 New Member

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    The carbs on these things must be pushed onto the int. manifold as far as they'll go, and then tightened (while still pushing it on).

    You can also try squirting a thin stream of water where the intake man. and the carb join together with the motor at "idle". If it dies, stumbles, or speeds up, you've found an air leak. Note: just don't spray any water in and around the CDI or the magneto (L.H.) side of the motor (unless you've carefully sealed the mag cover and CDI wire rubber grommet which, btw, should be done before riding in wet weather)
     
  11. tomcfitz

    tomcfitz New Member

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    See, one of the issues is that it won't idle at all, as soon as the clutch disengages, the engine dies. ****, it dies faster than it did when I pushed the kill switch.
     
  12. FMB42

    FMB42 New Member

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    Then lock or pull in the clutch while you test for vacuum leaks...
     
  13. mapbike

    mapbike Active Member

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    So you're saying that you can ride the bike and it runs ok until you release throttle and pull in on clutch lever?

    So you can pedal up to a bit of speed, release the clutch and it starts and you can give it gas and it goes but as soon as you let off gas and pull clutch it dies?

    Remove the air filter and look at the slide in carb and see if the idle screw is actually holding the slide open at its bottom edge, if the slide is all the way down when you try to adjust the idles screw in it will press against the side of the slide and will not raise it, twist the throttle to wide open and then try to screw in the idle screw, sounds like you have an issue with proper adjustment of the idle screw.

    Map reddd
     
  14. tomcfitz

    tomcfitz New Member

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    No, it doesn't accelerate or do anything except turn over as the wheel spins it. I think it's flooding pretty badly.
     
  15. mapbike

    mapbike Active Member

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    Is the spark plug really wet with fuel when you take it out after trying to start the engine?

    If it is either you're getting to much fuel and flooding as you suspect or the plug is wet because your not getting anything fire from the ignition.

    If the plug is dry when you check it then tbat is a sign you're not getting fuel into the engine.

    Map
     
  16. tomcfitz

    tomcfitz New Member

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    Could it be that I put high octane fuel in it? I just siphoned some gas out of my car and added two stroke oil to a ratio of about 40:1
     
  17. FMB42

    FMB42 New Member

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    Yes, that could very well be your problem. Over time auto fuel tanks can accumulate a lot of water. This water settles to the bottom of the tank (which is usually a few inches above the fuel pickup). Hence, siphoning gas from your auto can result in water fouled fuel.

    Anyway, drain your tank, fuel line, and carb and try starting over with fresh gas from a gas station. This may not fix it, but it sure can't hurt...
     
  18. tomcfitz

    tomcfitz New Member

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    It should have siphoned from the top; I had just filled my car up the day before, but I'll definitely try it.
     
  19. Jumpa

    Jumpa New Member

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    gas petcock sound partially plugged to me or the fuel filet did you use the stock gas line I've seen that flimsy stuff collapse in on itself more than once... also seen it cause a fire , Did you install the white screen filter that screws directly into the petcock these are vital to function ?
     
  20. Jumpa

    Jumpa New Member

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    OHHH OK ...So your not even starting then right ??? If not . pull the plug out rest it on the head ..spn rear tire see if there is spark !!
    first 3 things to check if bike will not start
    1st check spark
    2nd if there is spark fuel
    if fuel and spark then AIR

    If you do these 3 steps correctly you will either find out your problem.

    possible culprits..
    kill switch could be stuck in,
    magneto could be bad.
    Wires could be touching plug boot is not connecting (twist plug wire clockwise on both ends to ensure proper connection ,
    Do you have a multimeter?
     

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