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Carb tips and tricks, 1st: throttle shaft butterfly screw removal

Discussion in 'The Garage' started by gggGary, Jun 23, 2016.

  1. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    While snagging parts for a member with a bent throttle shaft I came up with this simple tool/fixture, it really helped remove the screws with no drama even with "pre fuggled" phillips slots. Sorry grabbed the wrong camera got blurry pics, stick is about 3/4 x 1". Clamp it in a vice, butt resting on the vice screw for support. Just shaped a stick with hand tools, 15 20 minutes total, this will aid in assembly as well as removal. Note the groove to capture the shaft, slotted to clear the brass tube, and bit of a bevel on one side to clear the butterfly. This lets you really bear down on the screwdriver to save the slot without the need for three hands to hang on to everything or the pressure bending the shaft.
    DSCN0441.JPG DSCN0437.JPG

    Use some lube on the back of the screws before removal. They are staked, the lube helps keep from tearing up threads on the soft brass throttle shafts. Even better is to file away the staked part of the screws BUT this is fussy fine work, very easy to nick up the carb bore butterfly shaft etc. Don't attempt filing if you are not a bit OCD and willing to TAKE PLENTY OF TIME and care.

    When the screws and butterfly are out you need to carefully deburr the throttle shaft front and back, at the screw holes, there will be a bit of swarf sticking up that will scratch up the throttle body bushings on the way out of the carb.
    The throttle shaft is chrome plated brass, IE it's soft and easily damaged. Don't aggressively polish the butterfly, being brass it can quickly wear away, corners can round destroying the critical sharp edge needed to get the idle right.
    search terms
    BS34 BS38 bs34s bs38s butterfly throttle shaft tool oak wood vice clamp impact hand JIS phillips butterflies seal seals guide removal remove burr strip stripped drill stake staked gggGary OCD nuts LOL bit allen hex replace replaced pine flooring stick rod dowel. leak air idle vary runon hang plate bear leverage crack clink
     
    Last edited: Sep 9, 2017
  2. Thanks gggGary - I have the seals and new screws in my garage, now I think I'll tackle the final carb tweak!
     
    gggGary likes this.
  3. 5twins

    5twins XS650 Guru Top Contributor

    20,062
    12,018
    813
    I was going to build something like that and now that I see how nice it works, I will for sure. Could you possibly get some clearer pics detailing the top? The slot, groove, bevel, etc.?
     
  4. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    here you go. I sanded and filed a bit more, spose I should stain and varnish it next...
    shaft recess was just a couple swipes with a round metal file, the 2 screw dents were made as I tapped a phillips bit into the screw heads to reform them before removing.
    next one will probably be made out of a piece of oak flooring.
     

    Attached Files:

  5. 5twins

    5twins XS650 Guru Top Contributor

    20,062
    12,018
    813
    Very good, now to find the right chunk of hardwood, lol.
     
  6. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Just got these off flea bay, they arrived in 2 days from Miami.

    3mm / M3 - 0.5 – DIN 7991 Stainless Steel FLAT HEAD Socket Screws Countersunk A2
    ( 111915431421 )
    Length: M3 x 8mm
    Package Quantity: 20
    Delivered on Fri, Jan 13
    ITEM PRICE:
    US $5.11
    or 10 for $4.00
    Seem to be a perfect fit. use a 2mm Allen driver.
    DSCN6651.JPG DSCN6650.JPG DSCN6649.JPG DSCN6648.JPG

    [​IMG]
     
    Mailman and retiredgentleman like this.
  7. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Looks like a good fit and allen to get them tight. Red or blue locktite? Are the original screws staked on the threaded end ? Locktite or not........if those screws ever come loose on a running bike they will be sucked into the cylinder and, HOLY S##T !!!!! It happens.

    Scott
     
  8. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Yes factory screws are staked. often they can just be unscrewed anyways, no doubt better if the staking is filed away first. Last ones I replaced with mcmaster carr screws got blue locktite. Should be staked I think. I haven't found a staking method I am all that happy with.
    Here's a tool aircraft guys use.
    [​IMG]

    http://www.pilotshop.com/catalog/graphics/12-21528.jpg $142.00 !!
    wouldn't be a bad DIY tool project.
    A view on staking importance from the aircraft world. http://msacarbs.com/pdf/SB-15_O 081210.pdf

    2many showed a method that involved center drilling the screws first.

    Kind of an esoteric oil thread. http://xs650temp.proboards.com/thread/7041
    Screws backing out is rare, any method is better than no method.
    You can put a lot of torque on an allan wrench, remember the threaded shaft is only BRASS!
     
    Last edited: Jan 13, 2017
    TwoManyXS1Bs likes this.
  9. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

  10. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    Those flat head allen screws are just perfect!
    Yes, blue locktite is the thing to use.
     
    gggGary likes this.
  11. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    5,686
    1,210
    213
    S.W. MO
    You don't have to stake them from the ends. A spring loaded punch can be used the stake, spike, deform the threads from the side.
    You can find mild steel screws at ACE Hardware.
     
    gggGary likes this.
  12. 5twins

    5twins XS650 Guru Top Contributor

    20,062
    12,018
    813
    If you find that you really like those screws, McMaster-Carr has them in 100 packs for less than $4 .....

    [​IMG]
     
    TwoManyXS1Bs and gggGary like this.
  13. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    plus shipping..........
     
  14. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    It's a bit overkill, involves making a fixture to hold the screw, then bombsight center it in the drill press.

    MikesXS Throttle Screws Modified.
    Countersink face recut from 80° to 92°.
    Shortened from 8mm to 6.5mm.
    Ends center drilled to 1.2mm (0.048"), for staking.

    [​IMG]

    With the hole, the end is weaker, and would allow easier staking with a cone/dimple stake tip, perhaps welded to the tip of long-nose visegrips. Just a mild swelling of the hole would do it. The hole is also a pilot hole if the screw needs to be drilled-out...

     
    Last edited: Jan 15, 2017
    Mike G likes this.
  15. Bob Kelly III

    Bob Kelly III Ranch Kid from way back,.... that got Old !

    LOL Bomb sight Centered is right 2M ..... I doubt I could get them that accurate !
    although I do now have a HF mini-Drill press that spins true....( given to me from my Father in Law) Unlike my shopsmith drill press !
    .... but I think I would just take a small dull chisel turn the butterflies sideways and take one whack with a small hammer and just try to off set a single thread ..... or as I have been doing the past 50 years, just flatten the tops of about 3 threads.... it won't come out again without destroying the throttle shaft though.....
    Gary..... your idea of using allen head screws for the throttle shafts is brilliant ! but it would take a ball end allen wrench...or swivel end as some call it...... so you need to make sure you have one of those on hand.
    .....
    Peanut,Gary ..... the Stick in the carb is another Fantastic idea ! THANK YOU !
    I will make one so it's on hand ! !!!!!
    ......
    the more I work on the XS650 the more I see the need for a good Powerful Dremel tool...one with guts ! or a drill snake and chuck for 1/8"
    cutters....
    maybe Santa Claus will bring me one if I'm a good boy !
    ....LOL
    Bob......
     
  16. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    5,686
    1,210
    213
    S.W. MO
    It doesn't take a ball end Bob. A straight long shaft will work.
     
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  17. Bob Kelly III

    Bob Kelly III Ranch Kid from way back,.... that got Old !

    Ahhh...ok I haven't had mine off so I wouldn't know...thanks for the info. ! I wondered how a phillips would fit at that angle but evidently there is enough angle if you lean the screwdriver against the bore of the carb !
    Kool !
    Bob.......
     
  18. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Bob, you'll want to tighten the butterfly plate screws while the butterfly plates are fully seated in the carb bore. The driver shaft will be almost parallel with the bore (off by about 12°), perpendicular to the plates...
     
    gggGary likes this.
  19. Bob Kelly III

    Bob Kelly III Ranch Kid from way back,.... that got Old !

    Thanks 2M !
    after snapping the butterfly a few times right? get them almost snug then snap them a few times and make sure they close completely
    Then tighten them ...... that's how I understand it ! LOL
    .......
    I remember doing the seals on a bike carb once and it was an ordeal.... got it back together and the butterfly would not close all the way...
    had to take and loosen the butterfly screws and work the butterfly plate over with a screwdriver and then re tighten....
    that worked..... at the time I didn't know about the snapping trick ! to help center the butterfly.
    .....
    Bob....
     
    gggGary likes this.
  20. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    gggGary likes this.

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