Cant get it to idle

Discussion in '2-Stroke Engines' started by AgusBarcia, Aug 16, 2016.

  1. AgusBarcia

    AgusBarcia New Member

    So i bought a used bike, and i cant get it to idle. I'll attach photos of the carb.

    When it's cold, if i start it with the choke on, it starts right away for a few seconds and then it dies.

    If i remove the choke then, it will only start when its going faster and the rpms are higher. I cant get it to idle, and the bike accelerates in rpm, drops and then dies. I already changed the intake gasket. If i give it gas it gets to high in rpm, if i let the gas go, it comes down and dies. I can accelerate it when its coming down, and it will mantain the rpms for a few seconds, and then accelerate in rpms.

    What do you ppl think? Bad jetting, air leak, or pos carb?
     

    Attached Files:


  2. AgusBarcia

    AgusBarcia New Member

    So i found something out, prolly has nothing to do with it. The floater bowl (idk how its called) seems to have a minor leak on the gasket. But the thing is, that if i close the fuel tap on the fuel tank, i cant even get it to start for a second, as soon as i give it gas, it starts.
    The stem that goes on the bowl with the jet, does it need to be submerged on fuel or not? Could it be that the level of fuel is not enough so that it cant get fuel on the intake at low rpm? I did clean it and i can blow through the jet, so i know its clean. I'm gonna draw what i mean as best as i can on paint.
     

    Attached Files:

  3. gary55

    gary55 Active Member

    The jet needs to be completely submerged in fuel. The symptoms you describe are similar to when you shut the gas off to a running engine. As the fuel is depleted from the bowl just before it dies it will rev up cause the jet is sucking air in with it's last drops of fuel. It acts lean like a brief vacuum leek. Make sure nothing is hindering normal fuel flow into the bowl, and re-adjust float to sink that jet, make sure the carb is all the way onto the intake and tight. You should be off to the races.
     
  4. AgusBarcia

    AgusBarcia New Member

    The float is not adjustable, but it didnt have a jet. So i jb welded one, and see how it goes from there. Also i was reading on this carbs, and they have a brass pipe with atomizers, where should they point? to the air filter, or to the intake?
     
  5. gary55

    gary55 Active Member

    Well ya got me bud. What kind of carb is it cause every one I've had the the floats were adjustable.
     
  6. AgusBarcia

    AgusBarcia New Member

    So, i got it to idle a bit high today, and when i rev it, it takes a few seconds to lower the rpm. So im guessings its rich, so gonna go buy a new smaller jet, and see how that works.
    The carb is a chinese copy of a Dellorto SHA. I has the float and the needle connected, so there is no way i can change the height at wich it closes. I could get a longer or smaller needle, but ill give it a try like this.
     
  7. gary55

    gary55 Active Member

    Ok I stand corrected. I have a SHA clone but I never checked out the float to needle connection. I learned something new today. Generally when it takes a long time for the rpm's to come down after reving it indicates a lean mixture. The engines tend to run a little richer as they warm up. On the carbs that have a needle adjustment I get them running and warmed up. Then I crack the throttle full open really fast. If it has a hesitation or kind of a bawk then revs up real fast and take a long time to die back down they are to lean. Your only adjustment is changing jets so I would try this, and if you put in a fresh plug and run it for a bit you can read the plug for further insight to your mixture. There's a ton of info if you google reading 2 stroke spark plugs. Might have some of that jb you used blocking flow as well. that would make it lean.
     
  8.  
  9. AgusBarcia

    AgusBarcia New Member

    So, gave it a ride today, on the block.
    What do you think of the plugs? Is it alraight? When i took it, it was really hot ,i had to use a cloth to remove it.
    Also couldnt make it idle, it sometimes idles fast, sometimes it dies... i guess i have a leak somewhere.
     

    Attached Files:

  10. Frankfort MB's

    Frankfort MB's Well-Known Member

    I'm sure it was hot because these motors run about 275-300 degrees!!

    That plug looks good surprisingly, im thinking your oil mixture off maybe??? I'm not sure:)
     
  11. AgusBarcia

    AgusBarcia New Member

    I used 40cc for every liter of fuel.
    Thats 1:25, Maybe the fuel is all right, there is some leak somewhere, gonna test it tomorrow, with a wire connected, instead of the accelerator, just to make sure thats not the problem. I did check it before installing it, and it worked fine, but maybe with the vibrations its not working properly.
    Also the carb is tilted, cuz the frame tilts the engine. Gonna make new engine mounts, and fix the carb bowl leak, and gonna see if it that helps.
     
  12. Frankfort MB's

    Frankfort MB's Well-Known Member

    Have you adjusted the idle speed?
     
  13. AgusBarcia

    AgusBarcia New Member

    I have messed with the idle screw, but it idles sometimes perfect, for a few seconds, and then it dies, or it just idles high. So no real use for it. Its just random. My guess is that as its tilted the bowl, a few degrees, maybe it isnt working as it should at idle. Sometimes im riding and it randomly dies, also the fuel cap, isnt letting air in, so i had to un screw it, so that fuel got to the carb. So many things to do, the joys of used cheap china bikes.
     
  14. Frankfort MB's

    Frankfort MB's Well-Known Member

    There's your problem!! The fuel is getting locked because the cap isn't venting

    Try to take the cap off and ride it see if that what your running into
     
  15. AgusBarcia

    AgusBarcia New Member

    All the tests, were done with no cap on. Because i knew that wasnt venting.

    Also im seriously considering, getting hydraulic front brakes... This thing doesnt stop.
     
  16. gary55

    gary55 Active Member

    Not sure what color the plug is. It looks grey to me. If so your running lean. it should be a chocolate brown. Does it hesitate or bawk when you crack the throttle wide open real fast when warmed up? These carbs are finicky at idle. I have read where a guy messes with the idle jet with a micro drill, but that is above my pay grade. I can't find the sweet spot on mine so I just set the idle a little high. If it's lean you want to get it corrected or you could fry it. What shape is the plastic sleeve where the carb goes onto the intake in? If it is all beat up you might be getting a leak there. I don't think it's the carby's angle causing your problems cause I think mine is angled more than yours.
     
Loading...