Fast Carb Question

Discussion in 'Old's Cool' started by Stagehand, Mar 16, 2007.

  1. Stagehand

    Stagehand Imperfectionist

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    its not a fast carb, but this question is pretty quick:

    I'm disassembling the carb right now, and I've got it down to the last thing.
    That would be the large needle. I can't get it out of the cylinder. Unless I'm mistaken there is a flathead screw down the small diam tube that will release it, yes? Is my screw just real tight?

    Or: how do I get the needle out?

    Thanks--

    J

    oh, yea.. this is a stock Bing CV off a '90 PD. thx.
    #1
  2. Poolside

    Poolside Syndicated

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    <BR>You mean the needle valve that sticks out from the bottom of the slide?

    If so . . The needles on the CV carbs that I've repaired were held in place by gravity.

    - Jim<BR><BR>
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  3. Stagehand

    Stagehand Imperfectionist

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    I may have answered my own question, but on the Max BMW diagram

    [​IMG]

    I think the problem lies around part #20. cant get that bugger to move. ANd therefore the needle wont come out. I'm going to go get a bigger hammer and try that.
    #3
  4. wintonio

    wintonio last of the Dum Dum Daze

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    did you try any loosening oils? As someone who has destroyed several stuck carb components lately, take ol' Ben Franks advice: Haste makes waste; hell, at least it is an sluminum part, and not that crappy self destructive brass!
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  5. Stagehand

    Stagehand Imperfectionist

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    as much WD40 as doing it in the living room will allow, and as far as haste: sage advice. Carrying on.
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  6. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

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    Boil it in water for 10 minutes or so, wrap it in a dishtowel and try to loosen it. Make sure the screwdriver fits properly, if you need to grind it down to get a tight fit in the slot do that. If after a couple tries it is still stuck, put some oil on it and let it sit overnight. Also, use a screwdriver with a boss so you can put a wrench on it. Not to apply gorilla torque but so you can concentrate on keeping it snug in the slot.
    #6
  7. Stagehand

    Stagehand Imperfectionist

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    its being unreasonable.

    It wont submit to heat or noxious chemicals.


    or having insulting remarks shouted at it, either.



    even the dogs left the room.








    :bluduh
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  8. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Here's the trick: The needle is held in there by two straight pieces of wire that interlock with the notches.

    The notches on the needle are 90 degrees from each other. So here's what you do: Your needles are probably in the third notch, so you'll have to do this a couple of times - twist the needle 90 degrees and pull gently on it while twisting. You'll feel it snap into the next notch. Do that again to get it into the first notch. Finally the last time it'll come out.

    Once you get it out it'll be obvious. Pretty simple really.
    #8
  9. notarex

    notarex Can U taste the waste?

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    It took me a while to comprehend the first time I did it, but tvrla is correct. Force will only cost you money, finesse is the key here- Good luck!
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  10. Stagehand

    Stagehand Imperfectionist

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    So are you saying that I dont need to mess with the screwplug at all? (part #20, above)

    I think I understand what youre saying about the notches, but that seems odd.. the new ones aren't devised that way.. and I dont recall the others I've seen to be that way-- they were just concentric rings in the top of the needles... not squared off on the sides.
    Possibly I've misunderstood you, though.

    I'll be taking the other one apart only this far, to check it against.

    My gut feeling is that the screwplug backs out, and the needle and retaining ring just fall out the top. I've fallen into a stuck screw gumption trap.

    Thanks for your help, though!

    J
    #10
  11. R-dubb

    R-dubb Dubbious Adventurer

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    It's not a matter of pulling. You twist the needle. Clean it of oil so the surface is not slick. Use a rubber glove and you should be able to twist with your fingers. If not use pliers with a rag, twist hard, pull gently. It will click loose one notch at a time. The notches are 90 degrees apart. There is no set screw or any fastnerer other than the spring clip inside that opens as you twist. Putting them back in the correct position is tricky because you have to count the 90 degree twists to know which notch is engaged.
    #11
  12. datchew

    datchew Don't buy from Brad

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    did you try heat yet? Naturally, make sure no excess gas resides, but maybe even holding a match to it will loosen it up.

    Am I reading this right that the needle itself won't come out or that the part you showed in teh diagram won't come out.
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  13. widebmw

    widebmw Been here awhile

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    STOP
    You are talking about 2 different carbs.
    The 32mm Bings have the screw in the slide that holds the needle in.

    The 40mm bings are the ones that you turn the needle to change the setting or remove it.
    #13
  14. Stagehand

    Stagehand Imperfectionist

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    Yes, thanks, its the 32's... those are stock for the '90 PD, correct?

    Dat: its the screw that wont come out.
    Yes to heat, yes to pentrating oils. No to success. At this point, I definitely need a new screw plug. Hopefully will get it out before I need a new slide.

    We shall overcome. :deal


    Hey-- RocketJ? In the very back corner of my head I remembered I read here somewhere about the two small flathead screws holding the throttleplate to the throttle shaft being Peened, and the ends need to be ground off to avoid trashing the tiny fine threads on the throttle shaft upon removal... Is this true?

    And also that they need to be peened again when installed to insure they dont back out and get sucked into the cylinder. Truth, or airhead legend?

    Throttle shafts are relatively cheap, I'm not so concerned if I ruined the threads for the lesson. Stupid Slide's for this carb damn near 1/4 the price of a brand new carb, and thats not even my fault, so I'm pissed.

    thank you thank you.

    J
    #14
  15. widebmw

    widebmw Been here awhile

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    Yes the 32's are stock on the US models the 40's were stock for the rest of the world.
    How about cold, dry ice ? then hot ?
    Easy out ?
    #15
  16. datchew

    datchew Don't buy from Brad

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    Damn. Sucks that it's stuck.

    If it were me, I'd probably get impatient by now and that's always my signal to let it sit for a little while. Maybe a full day or 2 with penetrating oil.

    then, i'm assuming the screw is brass and the portion it threads into is aluminum... i'd get some sort of drift and after heating again, lightly bang on it with a hammer. Just keep tapping, not enough to deform, but just over time, with repetition, to break the bonds of whatever is holding it in place.

    Good luck. If you get a chance to take a picture, i'd love to see it.
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  17. Stagehand

    Stagehand Imperfectionist

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    Datchew--

    I'll surely try to post some pics for you. I'm also gonna hit you up for some advice when I put them back together and need to tweak them.

    :norton
    #17
  18. datchew

    datchew Don't buy from Brad

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    Anytime bud. pm, email, or post here. I can send you my phone # if you want. I'm certainly not the most knowledgeable one here on such matters, but it is fresh in my mind.
    #18
  19. wintonio

    wintonio last of the Dum Dum Daze

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    I know exactly what you are talking about. I mean precisely. The screw is aluminum, and not brass. I recently had some severe (to me) carb woes, and now have intricate knowledge of the Bing 32mm carb... not that I know how to sync it or anything (soon to be paging Datchew), yet, but I bet I could disassemble and assemble them blindfolded. Anyway, other than telling you to be patient, followed by a display of violence and brute strength, I will offer no hack advice (because I have stripped several carb screws already).
    IF you F yours up, PM me, I just might have an extra slide laying around

    Wintonio
    #19
  20. wintonio

    wintonio last of the Dum Dum Daze

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    Any luck?
    #20