Carb Question...

Discussion in '2-Stroke Engines' started by hargie12, Apr 21, 2008.

  1. hargie12

    hargie12 New Member

    Hey I have a question about the carb. I had some issues with a fuel leak earlier and seem to have it fixed but am curious about something else. I have a Kings with the generic carb. I have replaced the crappy stock fuel lines with tygon and have placed an inline fuel filter. When I am riding I have no problems but seem to have quite a bit of fuel backing up into the fuel lines ( no problem I hope) and a little while before I kill the engine I usuallyturn off the petcock and idle for a bit. What I want to know is when the petcock is off and the engine is idling shouldn't the fuel in the line continue to be used? Also when I kill the engine slowly the fuel moves from the line into the carb. Is this just refilling the bowl or is it leaking into the cyclinder or the primer valve ( is does leak a small amount)

    Any help would be appreciated ( you guys are great)

  2. quay1962

    quay1962 Guest

  3. hargie12

    hargie12 New Member

    maybe I need to be specific

    I have read through many of these threads and I understand the "toilet bowl" carb. I am concerned because the fuel left in the line after I cut to petcock off, runs into the carb after I kill the engine. What I am trying to distinguish is, when the petcock is off does it create a vacuum not allowing the fuel to flow. Then after the engine is killed the float allows the extra gas to empty into the bowl. I am certain that the quantity usually left would overflow the bowl and push the unused gas into the cyclinder resulting in...wasted fuel.
    HOLY COW:puke: I am sorry for writing a book but it seems that by being specific you get specific answers.

  4. spad4me

    spad4me Member

    I have a Kings motors with a similar set up.

    Over the weekend With the petcock off the fuel is pushed into the carb by gravity.
    A lot of priming is necessary on monday.
    I have obtained a carb off a weed eater. That is like a normal one using two adjustment screws and a pressure tap for the fuel tank.
    hopefully no more gasoline vapor odor for me.
    When I close the petcock and let the engine idle until it dies. It usually runs for quite a while.
  5. graucho

    graucho Active Member

    OK Hank here we go.:smile:
    I did a few tests for ya.
    Test 1. I started my 80cc (whatever) with the fuel line full. Then I turned off the petcock and let it run at idle. It ran for exactly 13 min 37 seconds. These things get good mpg so it takes quite a while to run the line and bowl dry at idle. It was running ruff for the last 6 min due to poor vacum flow.
    Test 2. I filled up the line and bowl again. Started it. let it idle for approx 5 min. Shut off petcock and let it idle for 5 min. Shut off the bike and yes, the carb slowly took in the gas for another 1 minute. I think until the float was full and shut off the gas flow.
    Test 3. I filled up the line and bowl again. Started it. let it idle for approx 5 min again. Left petcock open and shut off bike. Gas line once again slowly took gas for 1 minute until float was full, then stopped.

    So, from my tests, I feel your carbs needle isnt seating completely. No difference between tests 2 and 3. Remember these carbs are cheap. The carbs float needles are cheap. My needle seems to seat good but if I let the bike sit for 24hrs my fuel line level will also go down a little. (2") Here is a diagram I made to show you how to tweek your float adjustment slightly so the bowl will stop filling.___Good luck man. graucho

    Attached Files:

    Last edited: Apr 22, 2008