2005 CRF150F won't idle - SOLVED
  • 75sausage
    Posts: 6
    Joined: Wed Jul 04, 2018 10:59 am

    2005 CRF150F won't idle - SOLVED

    by 75sausage » Wed Jul 04, 2018 11:20 am

    Hello to all.

    I have a 2005 CRF150F with the idle issue (common topic it seems). I have read a lot of posts regarding this issue and most point to dirty, clogged pilot jet (my pilot jet and hole are clean). Here is a video link to my symptoms.


    Bike is jetted 42/115 with main needle set at 4th groove from the top.
    Pilot (air/fuel) screw 2 turns out
    Freshly cleaned and oiled K&N filter
    FMF exhaust.

    What I did so far: Carburetor stripped and ultrasonic bath cleaned (pilot jet cleaned twice at this point), inspected carb to head manifold and seals, inspected intake rubber boot. Replaced pilot (air/fuel) screw rubber o-ring.

    The symptoms are:
    0 choke - bike will not idle, and sputters heavily with throttle applied.
    1/2 choke - idles fine, and sputters slightly with higher throttle input.
    full choke - idles and revs perfectly.

    Any ideas what would cause this?

    Thanks
    Last edited by 75sausage on Tue Jul 10, 2018 10:12 am, edited 1 time in total.
  • Aussiecrf230
    Posts: 1962
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2005 CRF150F won't idle

    by Aussiecrf230 » Wed Jul 04, 2018 3:12 pm

    Jetting sounds ok. Use a syringe and confirm fuel can go in through idle jet and out through idle drilling in carby mouth. It definetly sounds like the fuel is not getting through or an air leak creating a lean condition.
    Alternately confirm which position is choke on or off inside the carby. Seen it used back the front in the past which is why I ask.
    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
  • 75sausage
    Posts: 6
    Joined: Wed Jul 04, 2018 10:59 am

    Re: 2005 CRF150F won't idle

    by 75sausage » Sun Jul 08, 2018 9:24 am

    Thank you for a response.
    Choke is in standard configuration. Up=closed.
    I took tank of and drainded, cleaned the strainer, new gasoline added. I also readjusted the valves to .004 inch gap. I checked the float bowl fuel level using the clear hose method with carb leveled. Lastly i took pilot out, recleaned then sprayed through with carb cleaner spray tube, both, by itself and then assembled in the carb. Nice even stream comes out.
    With that said, i can't really see any light through the pilot jet. Similarly, i cannot run a tiny copper wire through it either. I use a conductor from a multistranded 14ga electrical cable.
    I tried to check for intake leak with starting fluid but did not get any indication of ingress.
    Oh, and spark plug is covered with black carbon after idling on choke. Running rich.
    I am baffled.
  • Aussiecrf230
    Posts: 1962
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2005 CRF150F won't idle

    by Aussiecrf230 » Sun Jul 08, 2018 4:35 pm

    Play it safe and replace the idle jet. I can see the .45mm hole through mine. Yours may still flow some fuel but may be restricted.
    Assume you have tried opening up the idle mixture screw to say 3 turns and see if there’s any improvement?
    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
  • 75sausage
    Posts: 6
    Joined: Wed Jul 04, 2018 10:59 am

    Re: 2005 CRF150F won't idle

    by 75sausage » Mon Jul 09, 2018 6:49 am

    I took the pilot out and inspected it with a jewelers loupe. I see a light through and, now, I was finally able to push the copper wire through. I saw some deposits on the sides of the jet bore so it is soaking in Seafoam cleaner. I will give it a final try based on your suggestions then go for a new jet if still not right.
    Image
    Image
    Image
  • 75sausage
    Posts: 6
    Joined: Wed Jul 04, 2018 10:59 am

    Re: 2005 CRF150F won't idle

    by 75sausage » Mon Jul 09, 2018 5:46 pm

    Even with a clean pilot like seen in the pics above, it still acts the same way. I tried messing with the fuel/air screw but it did not get any better. I'll go to the dealer tomorrow to pick up a new pilot jet.
  • Aussiecrf230
    Posts: 1962
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2005 CRF150F won't idle

    by Aussiecrf230 » Mon Jul 09, 2018 11:44 pm

    Did you see through the idle jet like this before?
    You may have got the bore of the idle jet clean but the cross holes still may be clogged. If there was junk in there make sure you are happy with any of the drillings through the carb as a bit of crud will drive you crazy.
    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
  • 75sausage
    Posts: 6
    Joined: Wed Jul 04, 2018 10:59 am

    Re: 2005 CRF150F won't idle

    by 75sausage » Tue Jul 10, 2018 7:31 am

    It'super clean, every hole and orifice. I just pulled the spark plug out after the bike sat overnight and its literally wet with gasoline. I am getting a feeling that its running way rich rather than lean.
  • 75sausage
    Posts: 6
    Joined: Wed Jul 04, 2018 10:59 am

    Re: 2005 CRF150F won't idle

    by 75sausage » Tue Jul 10, 2018 10:09 am

    As it turns out it was running rich ... primarily because I was trying to idle it with choke, butterfly valve closed.
    You were right to mention the choke position. I was assuming that the closed position = choke on when it is the opposite.

    These carbs work on the throttle cable operating the throttle slide, opening up the air passage and main jet needle to deliver more air and fuel. The butterfly choke valve remains fully open during normal operation, in contrast to other CV carbs. Closing the butterfly valve restricts the airflow, enriching the air/fuel mixture during choke ON setting. Other CV carbs operate the butterfly valve (throttle plate) to create the vacuum necessary to operate the throttle slide and needle to deliver more fuel.

    TL/DR: I confused the butterfly choke plate with throttle plate function. Lesson learned, choke lever DOWN is the normal operation.

    Thank you very much for your help mate.
  • Aussiecrf230
    Posts: 1962
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2005 CRF150F won't idle - SOLVED

    by Aussiecrf230 » Tue Jul 10, 2018 10:09 pm

    Well at least you worked it out. Either clean or put in a new plug if it has sooted up badly.
    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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