1. After 20+ years it's time to pass the torch. If you are interested in acquiring this forum please contact support@cv-performance.com for details. Any spam will be reported and blocked.
  2. Welcome to Bike Talk, a forum for all bikers and motorcycle enthusiasts. If you are new to Bike Talk, be sure to register for free and join the conversation.

    There's always someone around willing to help out with questions or give a friendly wave back. All Harley and metric riders are welcome.
Bike Talk Motorcycle Forum is For Sale Welcome to Bike Talk

Carburetor problems

Discussion in 'Motorcycle Tech Talk' started by Flfatboy, Dec 22, 2008.

  1. Flfatboy

    Flfatboy New Member

    Joined:
    Dec 19, 2008
    Messages:
    2
    Likes Received:
    0
    I rebuilt the Kehin carb on my 1995 Fatboy. For some reason after reassembly the bike won't run in the midrange. It just stalls when I open the throttle slightly. However, the bike will run at slow idle and wide open. The slide valve is opening but it is almost as if it isn't getting any gas and just stalls. I didn't move the cir clip on the needle valve. It is in the same position as it was before the rebuild. I have had it disassembled no less than 20 times and can't seem to locate the problem. I am really frustrated and hope someone will have some suggestions on what I should try next.
    Flfatboy, Dec 22, 2008
    #1
  3. hotroadking

    hotroadking Super Moderator Staff Member

    Joined:
    Jun 16, 2004
    Messages:
    13,682
    Likes Received:
    584
    Location:
    Mouseville USA
    Check the vac lines and caps be sure everything is as it should be.

    Possible fuel line collapse?
    Check fuel flow.

    Check float level, be sure float is moving.

    Clean out jets with some compressed air be sure jets are clean.
    hotroadking, Dec 22, 2008
    #2
  4. HarleysLR

    HarleysLR Active Member

    Joined:
    Jun 14, 2007
    Messages:
    2,113
    Likes Received:
    13
    Location:
    Colorado Springs, CO
    Check the rubber diaphram at the top of the slide. Hold it up toward a bright light and look for a pin hole or tear of any size, Vacumn is what makes the slide go up. Even with a small pin size hole you lose vacumn. A jet may be plugged and or check the needle seat on the fuel inlet and fuel bowl settings. Just run through the complete process again according to the shop manual? Let us know what you find.
    HarleysLR, Dec 22, 2008
    #3
  5. chucktx

    chucktx Moderator Staff Member

    Joined:
    Jul 5, 2005
    Messages:
    12,545
    Likes Received:
    10
    with the cover off and engine off, twist the throttle and see if gas is squirting into the throat of the carb. if not the accelerator pump is not working. i have seen the rod slip out of the lever....itis not clipped in....and not be reinstalled in the rubber boot.....just a thought......it is going to be something simple/overlooked.....good luck!!:)
    chucktx, Dec 22, 2008
    #4
  6. ironhorse

    ironhorse Active Member

    Joined:
    Sep 20, 2006
    Messages:
    1,290
    Likes Received:
    5
    Location:
    I'm everywhere, I'm everywhere
    wasn,t thinking of the accl pump thats a thought, i was leaning to the jet, and vents with hrk and the fuel screen/filter at the petcock as an add on thought
    ironhorse, Dec 23, 2008
    #5
  7. kenfuzed

    kenfuzed Administrator Staff Member

    Joined:
    Jan 1, 2005
    Messages:
    10,513
    Likes Received:
    140
    Location:
    Las Vegas NV
    Agree, I'd check the accelerator pump to make sure its functioning.
    1. Check that rod is in place and can move freely
    2. Be sure the accelerator diaphragm is not cracked
    3. Check that the o-ring in the accelerator pump didn't fall out
    4. Check that the nozzle still sprays fuel into the carb
    Also good the check on the slide to make sure it is still able to move and the rubber isn't pinched as suggested.
    kenfuzed, Dec 23, 2008
    #6
  8. Larcus

    Larcus New Member

    Joined:
    Dec 23, 2008
    Messages:
    2
    Likes Received:
    0
    Been Here and Done This

    I am new here but I think I did the same thing to mine. After wearing the screws out on it pulling it on and off I found what I did wrong.
    When you pull the main jet and tube out there is another small piece that comes out too. The piece you can see from inside the carb that the needle goes through. If you put it in backwards it acts just like you described.
    By the way, Hello to all and Merry Christmas, Larcus
    Larcus, Dec 23, 2008
    #7
  9. duke76

    duke76 New Member

    Joined:
    Sep 20, 2006
    Messages:
    371
    Likes Received:
    0
    Location:
    NW Iowa
    I have messed with a few CV carbs on 4 wheelers but not many on cycles but I think Larcus is probably correct, I have not put it in backwards myself but I do think it is possible and probably would run crappy in the mid range it would be worth taking a look at, the tapered ends should be touching if it is the tube I am thinking about, Todd
    duke76, Dec 23, 2008
    #8
  10. kenfuzed

    kenfuzed Administrator Staff Member

    Joined:
    Jan 1, 2005
    Messages:
    10,513
    Likes Received:
    140
    Location:
    Las Vegas NV
    The part Larcus is referring to is the needle jet, but I've always called it the nozzle. Its actually more common to leave that piece out than to put it in backwards, since it doesn't always fit. Make sure the wide fared opening of the nozzle is facing into the carburetor venturi, held in by the emulsion tube.

    I've actually seen carburetors miraculously run for 100's of mile without that nozzle piece. It's main function is to assist the needle in metering fuel as well as to properly spray the mixture up into the venturi. Without it you would probably still get fuel delivered but not optimally.
    kenfuzed, Dec 23, 2008
    #9
  11. Larcus

    Larcus New Member

    Joined:
    Dec 23, 2008
    Messages:
    2
    Likes Received:
    0
    Actually it looked like the nozzle did not seal to the jet tube, by the way it is made. One side of it is cone shaped, the other is flat, so I guess it was like an air leak and not pulling gas out of the bowl. This CV was on my '02 sportster, the ones that like to backfire out the carb. when cold. At about 1/4 throttle, without the air filter on, it was a bit amusing seeing all the fire coming out of the carb.
    Larcus
    Larcus, Dec 23, 2008
    #10
  12. chucktx

    chucktx Moderator Staff Member

    Joined:
    Jul 5, 2005
    Messages:
    12,545
    Likes Received:
    10
    flfatboy, did ya get your problem worked out????:)
    chucktx, Dec 23, 2008
    #11
  13. Flfatboy

    Flfatboy New Member

    Joined:
    Dec 19, 2008
    Messages:
    2
    Likes Received:
    0
    Carb Problem solved

    It turns out that I did have the needle jet in backwards.Initially I was only able to insert the end with the smaller diameter. I believe there may have been a burr preventing the larger or correct end from passing through the opening into the venturi way. Out of frustration I reluctantly inserted the end with the larger diameter and forced it into the opening. This must have knocked the burr loose because now I can freely insert or remove the needle jet. I reassembled the carb and it runs great. Thank you for everyones input.
    Flfatboy, Dec 27, 2008
    #12

Share This Page

XenPorta © Jason Axelrod from 8WAYRUN.COM