Carby Carby gremlins? Why so unreliable?

Discussion in '2-Stroke Engines' started by Molotov256, Apr 1, 2009.

  1. Molotov256

    Molotov256 Member

    Hey all... I finally got my second bike up and running again (it hasn't been the same since it ran into a van...), but it just dies out about halfway around the block and then doesn't want to start again.

    When i first started trying to fix it, gas was leaking out of the carb and exhaust whenever the fuel valve was on, so I made several adjustments to the float, and that seemed to fix that problem. I took the spark plug out and let the engine sit for a few days to kinda dry out, and now it works... a little bit.

    I've tried switching spark plugs between my working bike and this one, and that didn't change anything, so I'm pretty sure it's a carb issue.

    The bike won't start with the choke on, it only works with it off, and it's pretty smoky when it runs, so i think I'm still flooding the engine or running it too rich, but I'm out of ideas as to what to adjust to fix it. Am I on the right track?

  2. fetor56

    fetor56 Guest

    Swap carbies & see if that narrows-down your problem.
  3. Old Bob

    Old Bob Member

    Sounds like there is foreign material in the inlet needle and seat assembly holding it open and flooding engine.
  4. Molotov256

    Molotov256 Member

    Hey all, thanks for the feedback! Sorry it took me so long to get back up on here - the weather kinda crapped up on me, and work has this nasty habit of stealing all my daylight hours.

    Anyhow, I got a chance to try Fetor's suggestion about switching carbs, and that still didn't do the trick. I did notice something suspect in the process, though.

    When the gas line is not hooked up to the carb, and i switch the valve on, gas spills out, as I'd imagine it should. However, when I attach the gas line to the carb, no more gas comes out - the hose doesn't fill at all. I had the same result with both carbs. Now this seems like the opposite of an engine flooding issue to me. WTF, mate? :shout:

    The good news is that after swapping carbs, the other bike still works! Woot!
  5. Old Bob

    Old Bob Member

    Thats actually a good sign. The air has no place to go so will hold back the fuel in the line, if it was leaking through the needle and seat the air trapped in the tube would go away.
    As soon as the float drops to fill float bowl in carb air will (should) purge itself past needle and seat in float bowl and fuel will fill line and subsequently fill float bowl.
    Now if its doesn't fill, then you may have an issue with the tank vent.
  6. stude13

    stude13 Active Member

    try pumping the little brass button a few times and watch the gas in the line.
  7. Mountainman

    Mountainman Active Member

    I would have an extra around

    it's the way I would go

    my friend down the mountain has a HT
    we changed his carb out a while back
    he got a new one for 15 bucks
    for that price wouldn't want to fool with one for too long
    wasting time is wasting money

    having a back up get's us back on the road
    then when we do have time -- play with the other carb

    ride that thing
  8. Molotov256

    Molotov256 Member

    Hmm... glad to hear the problem I'm having is a positive sign. You mentioned a tank vent problem, but I've tried removing the gas cap to vent the tank and that didn't change anything.

    I fiddled around with the metal piece that the float moves to shut off the fuel when it's full (pardon my lack of proper terminology) and bent it upwards a little bit so the float could rise higher, and that allowed fuel into the carb, but it didn't shut off, so gas started flooding out again. Sooo... I took it back apart, bent the float stop back down again, and now I'm back to no gas.

    Is there a happy medium that I'm missing, or do I need to look somewhere besides the float?

    Mountainman suggested getting a new carb all together, which sounds like a great idea to me. I'm just not totally sure this is a carb related issue at this point, since the carb from my other bike didn't solve the issue, either. What else should I be checking? I must be missing something here...
  9. Old Bob

    Old Bob Member

    If you swapped carbs and the problem remained there may have been gas left in the carb you swapped, in that case the fuel wouldn't run into carb until the level in the float bowl dropped to the point where the inlet needle opened, did you try starting it and letting it run for a while?

    If you don't have a manual with the float settings you can try this:
    Many floats (key word many not all) will be at the proper float height when you take carb and hold upside down so the float pushes the needle into the closed position, the top portion of the float should be parallel with the flange of the float bowl.
  10. fetor56

    fetor56 Guest

    If u swapped carbs & it didn't change anything it doesn't sound like a carb related issue(except for o-ringing the carb & i assume you've done that)
    Is the engine still doing the same thing(dies out about halfway around the block and then doesn't want to start again)?
    Was it running ok before u hit the van? any of these tests with fresh fuel cos fuel goes off with time,& from what i'm told more rescent fuels go off even quicker.
    Last edited by a moderator: Apr 12, 2009
  11. Old Bob

    Old Bob Member

    In post #4 he said:

    The hose wouldn't fill if the swapped carb was full of fuel. Which I why I responded with my post above.

    The question remains if it runs and is dying halfway around the block.
    Old fuel could be an issue, also the impact with the van could have jarred something loose in the fuel tank that blocks flow.
    Frankly I wouldn't worry about the hose filling,see if it starts and see how long it runs.
  12. Molotov256

    Molotov256 Member

    Ahh, I see what you mean - sorry - I'm still fighting my way up the learning curve.

    As of now, no, the bike won't start at all with either carb.
  13. Old Bob

    Old Bob Member

    Probably should go back to basics.
    1. fresh gas
    2. check for spark
    3. check filters/screens
  14. Molotov256

    Molotov256 Member

    Ah-ha! No spark!

    I tried swapping spark plugs between bikes, but can't get either to spark on the broken one. Does this narrow it down to the CDI?
  15. Ghost0

    Ghost0 Guest

    I think that the impact damaged your magneto, the CDI is easier to swap to see if that is it but I would check the wiring first, then check the CDI or mag.
  16. Old Bob

    Old Bob Member

    Check your kill switch too, theres a thread here about the Staton kill switches having issues.
  17. fetor56

    fetor56 Guest

    CDI or mag sounds promising....lucky u have a second bike to swap parts over.
  18. Molotov256

    Molotov256 Member

    One of the first things I checked after the accident was the wiring between the motor and the CDI, and it's all still connected... You guys are speaking of CDIs and Magnetos, but I was thinking those were the same thing. The CDI is obviously the black plastic box with the spark plug wire coming out of it, so is the magneto something in the engine?

    I'll search the forum for killswitch info before I hit the garage again, but if anybody's got a link to the forum Ol' Bob was speaking of, I'd appreciate a direct link!
  19. fetor56

    fetor56 Guest

    The magneto is inside the engine...u access it by removing the left/front side cover.
    Stick with simplest first....try swapping CDI's.

    PS....IF u have your kill switch connected disconnect it.....their cheap & nasty & i wouldn't trust them.
    Last edited by a moderator: Apr 18, 2009
  20. Molotov256

    Molotov256 Member

    Thanks Fetor... I'll try swapping the CDI first. I'm debating ordering a new one or disconnecting the one from the other bike and switching it over... I soldered all the connections, so switching them would be a pain, although not unbearable.

    As for removing the killswitch... I'm willing to try taking it out of the circuit for testing purposes, but how is one supposed to stop the motor without it? Do you just dump the clutch without any momentum to stall it? That can't be healthy.