100 wont idle without choke after carb clean
  • forschishord
    Posts: 11
    Joined: Sat Oct 26, 2019 8:32 pm

    Re: 100 wont idle without choke after carb clean

    by forschishord » Sat Nov 09, 2019 3:52 pm

    Seems to be a bit of difference in terms still so humour me so I know we are communicating correctly.

    Choke on equals butterfly closed, restricts airflow from aircleaner side into carb
    Choke off equals butterfly open, no restrictions in carb except throttle slide.

    Is that your understanding.
    So are you finding that the choke needs to be almost closed for the bike to run properly at any rpm? Or just to accelerate from idle.
    Does it run ok at idle, does it run ok at riding engine speed.
    What are you referring to as a flapper.
    Have you had a chance to confirm compression pressure.
    Can you post a picture of your carb.

    Sorry it is a bit long just trying to get all the issues straight in my head.
    You know what that's like at the moment.
    On the carb Ive got, when u push the lever down the butterfly opens; this i believe is choke on no airflow restrictions except throttle slide. theres a middle position where the butterfly is at a 45 degree angle, and a closed position which i believe is choke off and when i switch it to that position it dies. if i hold it between the 45 degree position and the closed position it will run and drop the idle, but as soon as i let go it closes and dies. this is on a brand new oem keihin carb i ordered at https://www.motosport.com/dirtbike/oem- ... crf100f%29 im not home right now so i cant take a picture but i will post one later. if when the butterfly is closed that is in fact choke on than im an idiot lol but i dont think thats the case with this carb... but ive been wrong before. the bike runs completely fine and i can tune the idle to a seemingly normal idle with that butterfly wide or at a 45 degree angle but as soon as its closed its dead. and i cant start it with it closed hot or cold which continues to baffle me as this is a new carb so nothing is plugged up. also i dont have a 16mm compression adapter so i havent done a compression test. very difficult to kick by hand and kicks firm when i start it, hot or cold. feels just like my friends crf100, thats why i got it because they are allegedly built like tanks.
    2008 CRF100
    2001 CMX250
    1986 CMX450
    1981 KM100
  • Aussiecrf230
    Posts: 1562
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 100 wont idle without choke after carb clean

    by Aussiecrf230 » Sun Nov 10, 2019 2:10 am

    Hate to tell you but your idea of how the choke works is incorrect.
    The choke is definitely on when the butterfly is closed and it chokes off the amount of air that can enter the carby. Easy way to remember how it works.

    The good news if you can get the bike to run well when the choke butterfly is open that your bikes engine is OK and the carby is working normal.

    If you can't get it to start from cold with the butterfly closed it is perhaps either not that cold or idle mixture is rich.
    If you can peak the rpm at idle when the idle mixture screw is between 1 and 2 1/2 turns out then an idle jet is about right.
    If you can't get it to stall by screwing the idle mixture screw to between 0 and 1/2 turn out the idle jet is to large.
    If you end up more than 3 turns out then the idle jet is to small and the screw Is likely to fall out.

    Once you are happy with it idling when hot and restarts happily when hot with no extra throttle then I would play with the clip position on the needle.
    Adjust the clip so it pulls cleanly between say 1/4 to 3/4 throttle.

    The main is set when using wide open throttle.

    Do these adjustments with everything together with a clean air cleaner as Neil stated in an early post.

    Let us know how you go and if you have any other questions.

    I would check the choke linkage as it maybe worn/out of adjustment on the older carb hence completely blocking airflow.

    I have always had to use fully closed to start when cold and warm up on half choke.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas
  • forschishord
    Posts: 11
    Joined: Sat Oct 26, 2019 8:32 pm

    Re: 100 wont idle without choke after carb clean

    by forschishord » Sun Nov 10, 2019 7:48 am

    Hate to tell you but your idea of how the choke works is incorrect.
    The choke is definitely on when the butterfly is closed and it chokes off the amount of air that can enter the carby. Easy way to remember how it works.

    The good news if you can get the bike to run well when the choke butterfly is open that your bikes engine is OK and the carby is working normal.

    If you can't get it to start from cold with the butterfly closed it is perhaps either not that cold or idle mixture is rich.
    If you can peak the rpm at idle when the idle mixture screw is between 1 and 2 1/2 turns out then an idle jet is about right.
    If you can't get it to stall by screwing the idle mixture screw to between 0 and 1/2 turn out the idle jet is to large.
    If you end up more than 3 turns out then the idle jet is to small and the screw Is likely to fall out.

    Once you are happy with it idling when hot and restarts happily when hot with no extra throttle then I would play with the clip position on the needle.
    Adjust the clip so it pulls cleanly between say 1/4 to 3/4 throttle.

    The main is set when using wide open throttle.

    Do these adjustments with everything together with a clean air cleaner as Neil stated in an early post.

    Let us know how you go and if you have any other questions.

    I would check the choke linkage as it maybe worn/out of adjustment on the older carb hence completely blocking airflow.

    I have always had to use fully closed to start when cold and warm up on half choke.
    man oh man lol. Im an idiot =DD =DD Ive got it dialed in nice now and she runs good. Im just still baffled that even with a brand new carb i cannot start it cold or hot with the choke, but it starts good choke off or in the middle position so im just gonna run it like that. Thanks for walking me through my idiocy! \:D/ \:D/
    2008 CRF100
    2001 CMX250
    1986 CMX450
    1981 KM100
  • Aussiecrf230
    Posts: 1562
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 100 wont idle without choke after carb clean

    by Aussiecrf230 » Sun Nov 10, 2019 12:43 pm

    Well don't feel too bad we all get ideas in our heads on how things work or at least should work. It could have been an electrical problem which can drive you crazy.
    Most importantly you have it running sweet, which is what this forum is about.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas

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