Wierd carb problem. (Bing CV)

Discussion in 'Airheads' started by JamesJWeg, Sep 5, 2004.

  1. JamesJWeg

    JamesJWeg "Speedy"

    Joined:
    Dec 9, 2003
    Oddometer:
    1,736
    Location:
    Edgefield, SC
    Now that we airhead junkies got a place to play. My R100RT sports it's stock Bing carbs, and around the 100,000 mile mark it started snapping ether the main jet needle itself or the clip which holds it in the slide. Both carbs are doing this and I am only getting 2 - 3 K miles on each needle. Right now I am loosing one about every 1K because first it's one side, then it's the other. It's getting really old and I can't seem to find any answers, anyone know what's up? It's bad when you are preping for a weekend ride and you make sure you got two sets of needles and clips cause it's likly that you'll break more than one in two days. :cry

    James.
    #1
  2. a_k_nicholls

    a_k_nicholls Been here awhile

    Joined:
    Oct 8, 2003
    Oddometer:
    291
    Location:
    Near Canberra Australia
    Sounds to me like as the piston is lifting the needle up its kicking ever so slightly sideways & loading up the needle & eventually causing it to snap.

    Check how much movement is in the piston as either the bore or piston itself is probably worn.
    #2
  3. arroyoshark

    arroyoshark Needing some space

    Joined:
    Oct 9, 2003
    Oddometer:
    2,130
    Location:
    Fin del Sendero, NM
    No bling-bling Bing...! :lol3
    #3
  4. Frank Warner

    Frank Warner Traveller

    Joined:
    Mar 14, 2002
    Oddometer:
    6,593
    Location:
    Sydney, Australia
    When was the last time you cleaned out the carbys ... could be some crud at the bottom of the needles' hole. Got some oil blow by? Then you will have crud. Unless you reroute the breather.
    Oh, you better find the problem and fix it before something finds it way to the inlet valve!
    #4
  5. JamesJWeg

    JamesJWeg "Speedy"

    Joined:
    Dec 9, 2003
    Oddometer:
    1,736
    Location:
    Edgefield, SC
    Cleaned the jet stack, pulled it and dissasembled it, nothing, looks fine, no trash at all, I got twin inline paper element autotype fuel filters post tank, and got no trash from blow by, that plumbing's a little differant now :deal . um, the motor has eaten several c clips :eek1 :eek1 :eek1 no harm done, I've pulled the jugs and checked. When I take it apart early it seems like there must be a lot of extra movement somewhere as the c clip ring is worn loose, it will wear till the whole shoulder is gone and it drops. So where do I look for wear and who can get me specs of what size those parts should be?

    James.
    #5
  6. Frank Warner

    Frank Warner Traveller

    Joined:
    Mar 14, 2002
    Oddometer:
    6,593
    Location:
    Sydney, Australia
    :scratch

    Ummm... some advise replacing the seat along with the needle as they both ware together.

    Is it the clip or its seat that is worn? ... If your have put in new clips and they are dropping out then I'd be looking at
    1) the seat ... means you need a new piston $$ ...
    2) the clip ... you certain you are gettting the correct clip?

    :scratch ... good puzzle ... may be the best place is the airhead list for this. Good Luck.
    #6
  7. JamesJWeg

    JamesJWeg "Speedy"

    Joined:
    Dec 9, 2003
    Oddometer:
    1,736
    Location:
    Edgefield, SC

    Ok, which part are you refering to as the seat? Here are the doc I've got on the carbs.

    http://www.edgefield.k12.sc.us/jjw/Stuff/94x.pdf

    http://www.edgefield.k12.sc.us/jjw/Stuff/64list.pdf

    The parts which are failing are parts #14b and #4, I am replacing these with OEM parts, and any time I am in there I replace both of those parts at the same time with new OEM. Mine has clip style #14b and retainer style #15b. These are 64-3 carbs. Could the problem be that parts #2, #3, and #10 are worn? Or would it be #13 that is to blame? I have spoken to Bing and they say mail them in and we'll figure it out. :splat sounds like a lot of money to me. FYI, the bike has about 140,000 miles on it now.

    James.
    #7
  8. Malindi

    Malindi Zen Adventurer

    Joined:
    Jul 9, 2001
    Oddometer:
    5,425
    Location:
    Vancouver, BC
    mm .. I've rebuilt upwards of 20 such carbs in the last 5 years and can't see how that could happen. Are you sure you have the correct parts? Is there dirt in part 15b that pushes the clip down and out of 14b? Don't tighten 15b too mcuh. Seated plus a very minor bit of pressure is enough. Are the dimples in the carb rubbers lined up with the carb correctly?
    #8
  9. Malindi

    Malindi Zen Adventurer

    Joined:
    Jul 9, 2001
    Oddometer:
    5,425
    Location:
    Vancouver, BC
    mm .. I've rebuilt upwards of 20 such carbs in the last 5 years and can't see how that could happen. Are you sure you have the correct parts? Is there dirt in part 15b that pushes the clip down and out of 14b? Don't tighten 15b too mcuh. Seated plus a very minor bit of pressure is enough. Are the dimples in the carb rubbers lined up with the carb correctly?
    #9
  10. Malindi

    Malindi Zen Adventurer

    Joined:
    Jul 9, 2001
    Oddometer:
    5,425
    Location:
    Vancouver, BC
    mm .. I've rebuilt upwards of 20 such carbs in the last 5 years and can't see how that could happen. Are you sure you have the correct parts? Is there dirt in part 15b that pushes the clip down and out of 14b? Don't tighten 15b too mcuh. Seated plus a very minor bit of pressure is enough. Are the dimples in the carb rubbers lined up with the carb correctly?
    #10
  11. JamesJWeg

    JamesJWeg "Speedy"

    Joined:
    Dec 9, 2003
    Oddometer:
    1,736
    Location:
    Edgefield, SC
    It's all very clean, I've rebuilt and cleaned them several times. Yes it is the correct parts, the dealer has even repaired it twice, they are at a lose as well. Part 15b does not tighten down on 14b, should it? The carb rubbers are lined up correctly. When holding part 13 with 14b, 15b and 4 assembled part 4 seems to have a lot of play. A few times the sholders on part 4 have worn completly off allowing it to drop. At other times 14b fails dropping 4 into the jet. Every time I replace 14b, I also replace 4 as well. This has happened so many times I have gotten it down to about a 10 min operation to replace 14b and 4 with new parts.

    James.
    #11
  12. Malindi

    Malindi Zen Adventurer

    Joined:
    Jul 9, 2001
    Oddometer:
    5,425
    Location:
    Vancouver, BC
    15b needs to tighten to hold 14b in place. The edge on 15b holds 14b in place, leaving 4 some wiggle room to move side to side, but not up and down, at all. If 4 can move up and down, even a millimeter, then 4 cannot ever be guaranteed to rise at the correct height. As well, if 14b is loose (up and down) in 13, it will vibrate and wear out the shoulders as you found and drop 4 into 2 and 3. 4 wears out together with 3 in normal circumstances only very slightly. 4 and 3 need to be replaced every 20K or so as a set, as 4 will wear due to rotational vibration and become out of round, letting too much fuel through 3. 14b is made of much harder material, hence wearing out 4. Normally, the fuel surface tension shields 4 and 3 from excessive wear. I think the fact 15b does not hold 14b down is your problem. Also remember that most mechanics never get to tinker with carbs and don’t get it taught in the BMW courses anymore.
    #12
  13. JamesJWeg

    JamesJWeg "Speedy"

    Joined:
    Dec 9, 2003
    Oddometer:
    1,736
    Location:
    Edgefield, SC
    Since the battery in that bike just went belly up I'll pull the carbs off and have another look soon. I'll take some pics of it so you can see if you see anything that I am missing. It's kinda funny, I've nearly been worshiped for fixing carb problems on other people's 64's, but mine keep failing. :huh

    James.
    #13