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Tips to Ensure that Carb Diaphragm Is Seated Properly

Discussion in 'The Garage' started by YL82, Jul 2, 2012.

  1. YL82

    YL82 Perpetual Restorationist

    Does anyone have any pointers on how to ensure that the carb diaphragms are seated properly all the way around circumference (including tab) just prior to putting on carb hats?

    I have new ones from Mikesxs and when trying to secure the ridges around the circumference, they just don't want to stay put. Seems to me that new diaphragms should mold nicely around the circum. and stay there long enough to get the covers on.

    Can diaphragms be heated a little to make them expand and more pliable or can some light coating of spray adhesive be used to them in place? Just brain-storming... I'm probably worrying too damn much about it, but I just don't have a warm & fuzzy when I'm securing screws.

    No - I have yet to start my XS650C for a true test, not that far along...

  2. Belle

    Belle XS650 Addict

    Follow the pix--
    I do it like this--
    #1 pix is dry carb
    #2 pix is stubborn diaphragm
    #3 pix is juice
    #4 pix is carb w/ a little of the juice added
    #5 is diaphragm settled

    Let the juice set & cure for specified time period--24 hrs--before use (after the diaphragm is tamed to the guide area--don't lock it up & try ta run gas through it), it will grip a little faster & I've been eager before w/out problems but if ya have the time use it. I might be sayin' that really badly.

    I turn mine over onto a sani place ta cure (after pix #5).

    Attached Files:

  3. Belle

    Belle XS650 Addict

    BTW--it only takes a little, ya don't want the juice squirtin' all over the place. Whenever ya seat the diaphragm it should settle into a nice clean bowl area because if there's any juice in that area it will stick right to it & cause malfunctioning diaphragm.
  4. The diaphragm pictured above is a total wreck! Punctured and torn in several places and well beyond salvage much less matching the operation to a paired carburetor. Diaphragms are not intended to be bonded to anything btw it's pressure fit on the slide and a compression fit of the lip in a grove with the top bolted on. See JBM Industries instructions for removal and replacement. Blue

    Last edited: Jul 2, 2012
  5. Belle

    Belle XS650 Addict

    Realize its torn & battered it was used for example purposes & no one bonded any part of it but the lip that gets nailed anyway
  6. gggGary

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

    They always go in with just a bit of coaxing. Put as much of the diaphragm as you can in the groove, put the cover down on it but a little offset so the part that isn't in the groove is showing, the cover will keep the back side in place. Then work the rest of the diaphragm into the groove as you slide the cover over it. Works every time. Always helps to start with the tab area first. a little silicone grease helps with the sliding thing. If you have some spray silicone, spray some into a container let all the solvent evaporate, use the silicon in the bottom of the container to lube the diaphragm edge.

    I've (cough) never glued a diaphragm.
    I also sincerely hope I never find one when I open up a set of carbs either.
    True story; a guy was buttoning up a set of KZ1300 carbs and his "friend" dropped a cigarette coal on one of his diaphragms while "helping".
  7. YL82

    YL82 Perpetual Restorationist

    As to my lame-brained "glueing" idea using spray adhesive, here's I what I was thinking:

    Note: No, I do not work for 3M or do I peddle their wares!

    Product: 3M 75 Repositionable.

    Description: Repositionable 75 Spray Adhesive is an adhesive that provides tape-like bonds on many lightweight materials. It adheres in seconds, yet has an extra-long tack range that allows you to lift and reposition materials. Excellent for production line work where parts are held in place temporarily prior to final assembly. Bonds paper, cardboard, acetate, foil, fabrics, sheeting, etc. Clear in color.


    30-40% Acetone
    20-30% Isobutane
    20-30% Heptane Isomers
    7-13% Non-Volative Components, Trade Secret (likely the sticky stuff)
    7-13% Propane

    I would think that the majority of this stuff would volatalize pretty quickly and/or be dissolved in gasoline.

    I had in mind to apply a light "film" of this stuff with a Q-tip, allow to dry and become tacky, then work in the diaphragm.

    Plausible Idea? Perhaps

    Am I personally willing to try it over the other suggestions? Nah...:D

    Attached Files:

  8. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    S.W. MO
    It has been said, but I'll reiterate.
    Other than patience, nothing is need to get them lined out.
    Acetone, eyther, solvents of any kind are NOT good for the thin diaphragm.
  9. YL82

    YL82 Perpetual Restorationist

    I will heed your sage advice, weekendrider.

    Out of curiosity, what type rubber (presumably synthetic) are the diaphragms typically made of?


    Viton (fluoroelastomer)?

  10. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    S.W. MO
    Sorry I can't answer that. I don't have any formal education (10 grade).
    But life is a school. I can relate the damage I've done.
    An accidental spraying with ether made them as crisp as potato chips.
    Acetone will dry them also.
    I've used Naptha gas(14 lb. gas at the racks) to clean the dark diesel stain around the filler caps. Cuts it quick and any dirt has the "oil" dried out of it so a quick hit with the water hose takes off the dirt. Quick, cheap and dirty for the enviroment.
    I also tried getting rid of a big ant den with it.
    Poured about a half a cup down the hole. Took a rag on a 15' pole to light it.
    I wasn't far enough. The fireball consumed most of my beard and any hair not under my cap. And I had rosey cheeks for a week.
    That Naptha shit has some serious combustion properties.
  11. Belle

    Belle XS650 Addict

    Where's the camera when ya need it
  12. gggGary

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

    Did it kill the ants? If so it was a roaring success. :wink2:
  13. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    S.W. MO
  14. YL82

    YL82 Perpetual Restorationist

    I'm thoroughly convinced what to do and more importantly, what NOT to do.

  15. YL82

    YL82 Perpetual Restorationist


    For clarification, are you saying to:

    1) Apply silicone juice around the "rim" and let it sit for 24 hours (before securing diaphragm)

    OR are you saying to:

    2) Apply silicone juice around the rim or circumference, then secure the diaphragm around it and then wait for 24 hours prior to placing on the diaphragm cover?

    #1, #2 or None of the Above? :)

  16. YL82

    YL82 Perpetual Restorationist

    Hey, bluebikerblan - My apologies - just noticed & checked out the link you sent to jbindustries.

    So are the CV diaphragms from Jbmindustries.com a better product that what Mikesxs peddles? Opinions?
  17. kvanderploeg

    kvanderploeg The Dutch Terror

    Have you tried putting the diaphragms in the freezer for a few hours (or overnight)?

  18. +1 kvanderplog on the freezer trick, that has worked for me many times.

    Use a little tacky grease, vaseline, silicone dielectric grease, crisco to hold the diaphram in place.
    Gently blow compressed air into the carbs to check for smooth slide operation after you have them put back together.
  19. Some varied ideas here, though not really conclusive.... Back to patience manipulation ans a tiny bit of silicon grease, I'm going for the slide method.......

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