well another kinda disturbing find today

Discussion in 'Airheads' started by mfp4073, Dec 4, 2012.

  1. mfp4073

    mfp4073 Long timer

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    been fighting a weird symptom with my carb adjustments. The right side bing would not respond to the idle mixture screw and it took the idle adjustment to be not touching the stop to get them balanced. And then only by upping the left side so it idled at 1300 ish. Started by taking out the idle adjustment screw and was going to check the passages again. Then realized one of the butterfly screws was "hanging by a thread" :eek1 furthermore it was stripped so I could not just screw it back down.

    Ended up finding a counter sunk american screw that would slip in there and then put a nut on the back with locktite. It will cause a bit of restriction at the top end, but got me going. All I can imagine is that screw coming out and getting lodged in a valve and the engine going :puke2
    #1
  2. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    With a 40 year old machine you need to go through it with a fine-tooth comb and weed out these loose ends. You don't need to find them by surprise.... :D
    #2
  3. disston

    disston ShadeTreeExpert

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    Often the Butterflies get taken off because somebody wants to renew the O-ring. Then when reinstalled they have only replaced the O-ring with no regard to the special circumstances about this part. Those small screws were originally staked and they should never fall out unless a former owner has messed with them and did not properly reinstall them.

    Your repair is fine for getting it running. I think you should now rebuild both carburetor butterflys. To do this you will need new shafts (2), screws (4) and O-rings (2). If one of these screws gets sucked into the engine it can and most likely will ruin your day.

    You should be able to reuse the round disk.

    Check the budget and see what these all cost. When you are ready to do this we will cover the proper replacement of these screws for you.
    #3
  4. mark1305

    mark1305 Old Enough To Know Better

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    Good catch, Chad. That could have turned ugly in not many more miles.
    #4
  5. AK Bob

    AK Bob AKAM

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    To Fix it..

    Take a patern file or dremmel tool, cut the tip side of the brass screws right down to the rod. If you nick the rod no biggie, if you don't get all the peened theads.. You will pull a BOB.. (Strip the threads right out of the rod.) Then you get to talk to the nice folks at the bing agency and get a new throttle shaft, they also have a video on rebuilding carbs..

    If you were in the Airheads in AK. I'd show you how not to pull a BOB!
    #5
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

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    The shafts are pretty inexpensive - I got one from Hucky a while back for ten or twelve bucks. I don't even think they're much from the dealer.

    And it wasn't the re-installing that buggered the threads, it was the removal. Someone didn't know they're not supposed to come out, and man-handled them out of there. The correct stuff is pretty cheap, so just get it done right.
    #6
  7. mfp4073

    mfp4073 Long timer

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    Yeah, I am starting to wonder how long its been wobbling around in there. Another problem I have had is a variable idle. Sometimes one speed, sometimes other. If the screw moved in and out at times I am guessing it could change the amount of air getting past the butteryfly and thereby the idle speed. I actually hosed that carb several times with ether trying to find a leak, but never got a result. Its been driving me so crazy that I have considered replacing the carbs all together. Im not real sure how I never noticed the screw being loose. Had the carbs out and apart half a dozen times.

    At this time I am going to leave it. The only time this would have any effect would would be full wide open throttle and then that side would have a bit "less" flow. For my purposes its running great! Nice low smooth idle. Have never been able to get it to idle decent at anything below 1400 rpms and usually had an idle to off idle miss that was unhappy and rough.
    #7
  8. Chico

    Chico Thief and Saboteur

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    I had a screw like that come off the choke plate of a honda 90 when I was 16. Rebuild, check.
    #8
  9. mfp4073

    mfp4073 Long timer

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    I recently also found a stripped lifter set bolt (I am probably responsible for that one) and pulled out the helicoil on the right side valve cover center bolt (that was fixed with a nut ground down and slipped into the outside of the head and jb welded in place). Couple that with my starter issue, battery fail, and alternator failing and I have had a rather stressful several months with this bike.

    But now she is purring like a milk faced kitten and sooooo much nicer to ride now than the last 2.5 years and 24k miles :clap
    #9
  10. mark1305

    mark1305 Old Enough To Know Better

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    Hey Chad, are you still volunteering at the Museum? That airhead motor is enough like half of an aircraft motor, that some of the talent hanging around there could be a big help sometime. :wink:
    #10
  11. mfp4073

    mfp4073 Long timer

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    Still over there and now working on a couple of waco biplanes in merritt island actually! and yeah, I am now telling people that I am such an airplane buff that i bought a bike with a 2 cyl radial motor in it! :rofl
    #11
  12. mark1305

    mark1305 Old Enough To Know Better

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    I'll have to dig out a pic of my late father-in-law's Waco and PM it to you. He owned several tire stores and a recap shop around middle GA up until the early 70s. His "business" plane was a Waco biplane with fully enclosed cabin and a hired pilot. When he retired due to heart problems back then, he sold it to a Hollywood movie company/interest. The ferry pilot flew it into the side of mountain while crossing the Rockies with the expected outcome for both the plane and pilot.

    Are the Wacos you work on the Ride For Hire planes based out of here? :ear
    #12
  13. mfp4073

    mfp4073 Long timer

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    Thats kinda cool (well the ending sucks)

    Yep, thats us. One is red white and blue and the other is blue and gray (currently under restoration). :evil

    [​IMG]
    #13