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Thread: Fixing an idling issue

  1. #1
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    Fixing an idling issue

    First, I want to thank everyone that has taken time to respond to my posts. I know it's probably annoying having to hear from someone that is trying to learn and figure things out, but all of your help has made a big difference for me. I just finished installing my new Odenthal ez 206 motor mount, cleaned out the gas tank, gas can, changed all the fuel lines, got the chain tension set properly(I hope), got my carb cleaned out by the speed clinic up in China Grove, NC. The engine starts up great, sounds really good. After it runs, I drain the fuel out of the carb. The only issue I am dealing with now is that when I let the accelerator pedal go, the engine cuts off. I was just outside adjusting the idle screw while the engine was running with no luck. No matter where I set the screw, it keeps cutting off. The briggs racing website talks about the mixture screw as well saying that if that is not set properly(lean), the engine will cut off. I have not tried adjusting that screw yet, because I'm not sure if I should or not. Any suggestions would be greatly appreciated.

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    Turn the idle air screw in until it LIGHTLY seats, counting the rotations, it is usually easiest to go in half turns (180*) so you know where to put it back. Now reset the screw 1/4 turn more out, lets say it was 1.5 turns set to 1.75 and see how it runs, you can noww adjust that screw in or out to find the best setting, it will probably lie between 1.25 and 1.75 turns out. Take the air filter off you should be able to see the difference in height of the black slide as you change the idle stop screw, screwing it in should raise the slide.

  3. #3
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    He might be turning the wrong screw to set the idle. Idle screw controls the Idle Speed. Idle screw is more towards the front of the kart. Air mixture screw is more towards the rear and lower (closer to the ground). It also will affect idle speed but you just set it where it idles best. Most of the time, we end up with 1 1/4 to 1 1/2 turns out from LIGHTY seated on the air mixture screw. You can bounce back and forth peaking the idle speed with the air mixture then setting it at about 2000 rpms with the idle screw. There have been instances where we turned the idle screw all the way in to get it to idle. Remember, you never race at idle anyway unless you are REALLY, REALLY SLOW.

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    You are getting some good advise on here. Don't expect a racing engine to idle very slow, they just won't do it. )1Ron is dead on, I usually set idle at least 2000. IF you spin out you don't want the engine to stall either.
    Most strive to get the engine to just idle somewhere, but are serious about what is happening at wide open.

    Assuming that you have a 206, look at the front of the carb, there are 2 screws, the one on the left controls how much air get in low circuit at idle, if it smokes black turn it counter clockwise to lean the idle. The one on the right controls the height of the carb slide. the more you screw this one in (clockwise) more rpms you will idle.

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    You are getting some good advise on here. Don't expect a racing engine to idle very slow, they just won't do it.

    1Ron is dead on, I usually set idle at least 2000.
    Most strive to get the engine to just idle somewhere, but are serious about what is happening at wide open.
    Check or change spark plug.
    Assuming that you have a 206, and that there are no leaks, float set correctly, no kinks in fuel line, look at the front of the carb, there are 2 screws, the one on the left controls how much air gets in low circuit at idle, if it smokes black turn it counter clockwise to lean the idle. The one on the right controls the height of the carb slide. the more you screw this one in (clockwise) more rpms you will idle.

  6. #6
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    Ok, so what I am reading here is that I should be adjusting the smaller screw on the bottom left, the idle mixture screw. I was adjusting the screw on the top right, the idle speed screw, which increased the rpm's. I could hear it getting louder, but when I let off the accelerator pedal, the engine cut off. Adjusted that screw back and forth with no luck. I have been advised to never touch or adjust the mixture screw. Briggs racing website says on page 5 of the carb tunng guide that mixture screw is 1 and 1/2 turn. Is that what I should adjust it to from lightly seated? I'm assuming lightly seated means just barely screwed tight? How do you know that you have set the rpm's at 2000? I just had the carb cleaned out and a rebuild on it. I put on all new fuel lines. I do have another spark plug if needed. I have a feeling the mixture screw is the issue. Thanks again for all of the help guys. I really do appreciate it.

  7. #7
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    I've already told you that "Most of the time, we end up with 1 1/4 to 1 1/2 turns out from LIGHTY seated on the air mixture screw". I can't make it any plainer than that. It is an air mixture screw and the further OUT from lightly seated, the leaner the idle mixture. TURN OUT TO LEAN IDLE, TURN IN TO RICHEN IDLE. Or even easier to remember, turn Left to Lean, turn Right to Richen. Just semantics! Just make sure you measure it from the beginning so you know where the original setting is now.

    If you don't have a Mychron or some other tach, you will not know what your RPM is. Just make it idle fast enough so the engine does not die.
    Last edited by 01ron; 05-15-2018 at 08:13 AM.

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    ^ ...and slow enough that it does not engage the clutch.


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  9. #9
    4 Cycle Advanced User Jimbo's Avatar
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    If you have the slide needle set too lean you may have a hard time getting it to idle as well.
    If you would like to call me i can help.
    Jim
    Thank You to the 2017 206 Cup Grand National Champions for choosing Faster Motors
    Cayden Fretwell Sportsman Class Champion
    Emily DeMaster Junior Class Champion
    Grant Zimmermann Senior Heavy Class Champion
    Randy Raridon Masters Class Champion

  10. #10
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    Quote Originally Posted by Jimbo View Post
    If you have the slide needle set too lean you may have a hard time getting it to idle as well.
    If you would like to call me i can help.
    Jim
    If you could dm me your number. I would like to speak with you. Thanks.

  11. #11
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    I was just out trying to fix this issue. I turned the mixture screw very slowly until it was lightly seated. I then turned that screw out 1 and 1/2 times. Started engine and every time I let off the gas pedal, the engine would cut off. I adjusted the idle screw to try and get it to 200 rpm's. There was also smoke coming out from the exhaust holes. I am completely lost. I had the engine taken off the kart last week, cleaned everything, new mount. I'm sure I put everything back together properly.

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    his number is in his avatar

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    Sounds like your needle is set incorrect like Jimbo mentioned except maybe too rich vs too lean. Call Jimbo and let him walk you thru it. Be careful not to lose the spring clip that you will end up having to remove inside the slide (under the spring) to check the needle height. Seen that happen to many times. And the "C" clip on the needle will snap off while changing needle heights and it sometimes will disappear in a millisecond. Need to capture the "C" clip when removing it. And it's 2000 RPMs not 200 RPMS.

    On second thought, when you had the carb work done, how did you remove the carb to take it to them? Did you remove the slide and disconnect the throttle cable connection in the carb slide? If you did, did you ensure the spring clip under the spring that holds the needle in place was installed correctly? If not, the needle can just slide up causing the engine to run super rich at idle.

    You need one on one help. All this internet chatter seems to confuse you more than help you. Remember, the instructions given by someone who has done this thousands of times might seem plain and simple to them but to the inexperienced it can be very confusing. That's why I try to over explain.

  14. #14
    4 Cycle Advanced User Jimbo's Avatar
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    Thank You to the 2017 206 Cup Grand National Champions for choosing Faster Motors
    Cayden Fretwell Sportsman Class Champion
    Emily DeMaster Junior Class Champion
    Grant Zimmermann Senior Heavy Class Champion
    Randy Raridon Masters Class Champion

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    Crud in the Jets. Easy enough to fix . Remove bowl and remove emulision tube and clean the 4 little holes near the bottom. Yes, I know you had it cleaned but sometimes it's easy to miss or over look.

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    Quote Originally Posted by Jimbo View Post
    920-207-9180
    I will call you today.

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    Quote Originally Posted by 01ron View Post
    Sounds like your needle is set incorrect like Jimbo mentioned except maybe too rich vs too lean. Call Jimbo and let him walk you thru it. Be careful not to lose the spring clip that you will end up having to remove inside the slide (under the spring) to check the needle height. Seen that happen to many times. And the "C" clip on the needle will snap off while changing needle heights and it sometimes will disappear in a millisecond. Need to capture the "C" clip when removing it. And it's 2000 RPMs not 200 RPMS.

    On second thought, when you had the carb work done, how did you remove the carb to take it to them? Did you remove the slide and disconnect the throttle cable connection in the carb slide? If you did, did you ensure the spring clip under the spring that holds the needle in place was installed correctly? If not, the needle can just slide up causing the engine to run super rich at idle.

    You need one on one help. All this internet chatter seems to confuse you more than help you. Remember, the instructions given by someone who has done this thousands of times might seem plain and simple to them but to the inexperienced it can be very confusing. That's why I try to over explain.
    Here is the work that was done to the carb when I dropped it off to the speed clinic. This place was recommended to me by someone at the track that has been helping me, and also works PT at this place.
    Carb Rebuild
    206 Float kit w/needle and seat
    gasket-float bowl
    Briggs needle

  18. #18
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    Quote Originally Posted by Elmer Patterson View Post
    Crud in the Jets. Easy enough to fix . Remove bowl and remove emulision tube and clean the 4 little holes near the bottom. Yes, I know you had it cleaned but sometimes it's easy to miss or over look.
    Elmer, I will try and get some time with the kart today, and see if I can the part you are talking about. The bowl is on the bottom, but where is the emulsion tube inside that? And what should I use to clean those holes? I have some brake cleaner.

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    You will see two Jets the largest one is the emulation tube the little tiny holes at the bottom. 4 holes try to find a piece of fine wire to push thru holes carb clean will help

  20. #20
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    Quote Originally Posted by Jimbo View Post
    If you have the slide needle set too lean you may have a hard time getting it to idle as well.
    If you would like to call me i can help.
    Jim
    Jim, Thanks for taking the time to speak with me. The kart is idling. It did not cut off after I let go of the gas pedal. Here's what I did. I took the slide out, pulled the spring up, took the throttle cable out. I removed the v-shaped thing, then took the pin out. I removed the c shaped clip and moved it to the 2nd space from the top. I placed the pin back in the slide, placed the v-shaped thing back on top, placed the throttle cable back in place, slide back in place, and then closed up the top of the carb. Hopefully that was correct. Like I said, the engine did not cut off. I adjusted the idle screw to different settings to try and get it to 2000 rpm's, but the closest I could get it was 1400 rpm's. The idle screw is sitting just about flush. It would settle on 1400, but would jump to around 900,1100, then back to 1400 rpm's.

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    Where was the clip before you moved it?

    By the way, congratulations. I could actually follow every step in your post. Next thing you know, you will showing someone else new how to do it!

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    Quote Originally Posted by 01ron View Post
    Where was the clip before you moved it?

    By the way, congratulations. I could actually follow every step in your post. Next thing you know, you will showing someone else new how to do it!
    Thanks..The C shaped clip was towards the bottom of the rings at the top of the needle. I can't remember exactly where.

  23. #23
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    The further towards the bottom, the richer the bottom RPMs. Makes sense. Now that it is idling, you can tweak the air mixture screw very slightly either way to make the idle run the highest RPM then reset your idle screw if the RPMs increase to high. I usually peak the RPM then turn the air screw in just slightly clockwise to make it richer. Just enough to slightly drop the RPMs.

    Hope you are writing all this down or copy and pasting into a document for further reference.

  24. #24
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    1400 is a very low idle speed. I would want it higher than that.
    Thank You to the 2017 206 Cup Grand National Champions for choosing Faster Motors
    Cayden Fretwell Sportsman Class Champion
    Emily DeMaster Junior Class Champion
    Grant Zimmermann Senior Heavy Class Champion
    Randy Raridon Masters Class Champion

  25. #25
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    Quote Originally Posted by Jimbo View Post
    1400 is a very low idle speed. I would want it higher than that.
    It was recommended above to get it to 2000 rpm's. The reading on the mychron yesterday only got to 1400, but that was with only adjusting the idle screw. I will adjust the mixture screw today and see if that helps get it to 2000 rpm's.

  26. #26
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    Quote Originally Posted by 01ron View Post
    The further towards the bottom, the richer the bottom RPMs. Makes sense. Now that it is idling, you can tweak the air mixture screw very slightly either way to make the idle run the highest RPM then reset your idle screw if the RPMs increase to high. I usually peak the RPM then turn the air screw in just slightly clockwise to make it richer. Just enough to slightly drop the RPMs.

    Hope you are writing all this down or copy and pasting into a document for further reference.
    01iron, thanks for the advice. I will go out there today and adjust the mixture screw slightly either way and see how that affects the rpm's. I will keep adjusting it until I get the mychron to read at 2000.

  27. #27
    4 Cycle Advanced User Jimbo's Avatar
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    I'd go more than 2000. As long as you are below where clutch engagement starts you are fine.
    Clutch engagement should start somewhere above 3000.
    The higher idle RPM will prevent it from stalling for what ever reason.
    Thank You to the 2017 206 Cup Grand National Champions for choosing Faster Motors
    Cayden Fretwell Sportsman Class Champion
    Emily DeMaster Junior Class Champion
    Grant Zimmermann Senior Heavy Class Champion
    Randy Raridon Masters Class Champion

  28. #28
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    I tried adjusting the mixture and idle screw, and it would not idle anywhere near 2000 rpm's. It dropped from the 1400 I was at yesterday, to as low as 700. It would never go higher than 1400. Hopefully I'm not doing something wrong. Could the mychron unit not be getting an accurate reading?

  29. #29
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    Yes and it could be configured to read incorrectly. I am not familiar with MyChrons but there usually is a 2 stroke 4 stroke setting. You want 2 stroke if it is the same as an Alfano.

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    I know nothing about these engines but remember reading thishttps://karting.4cycle.com/showthrea...206-won-t-idle

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