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Aftermarket CV carb diaphragm replacements - anyone tried?

Discussion in 'XJ Technical Chat' started by cds1984, Apr 2, 2011.

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  1. cds1984

    cds1984 Active Member

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    Hi,
    Since I have holes in all my Mikuni BS34 and BS36 carb diaphragms I thought it might be best to take a look for the alternatives and ran into this website.

    JBM industries diaphragm replacements

    Looks good to me but I figured I'd ask the question whether any of the XJ'rs
    here have any experience with these replacements?
     
    cds1984, Apr 2, 2011
    #1
  2. wizard

    wizard Active Member

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    I havn't tried them myself, but it looks like you struck gold...
     
    wizard, Apr 2, 2011
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  3. cutlass79500

    cutlass79500 Well-Known Member

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    I have never personally tried them but i herd of a lot of virago owners using them
     
    cutlass79500, Apr 2, 2011
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  4. cds1984

    cds1984 Active Member

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    After reading about the process and all the other bits on the site I'm thinking they are going to work a charm too.
    Just ordered them.
    I'll do some pics when they arrive, of the procedure.
     
    cds1984, Apr 2, 2011
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  5. Ravenz07

    Ravenz07 Member

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    I guess it beats a 25 cent condom lol
     
    Ravenz07, Apr 2, 2011
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  6. RickCoMatic

    RickCoMatic Well-Known Member

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    Funny, ...

    Until introduced to this site, ... right now. I have never heard of them!

    At $20.00 a-pop, ... how can you go wrong?

    I'm going to try them out.
     
    RickCoMatic, Apr 2, 2011
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  7. waldo

    waldo Member

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    Great product!! you will not be disappointed.
     
    waldo, Apr 3, 2011
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  8. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    WOWZAS!!! Now where are the 28mm Mikuni parts?
     
    bigfitz52, Apr 3, 2011
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  9. Smooooth

    Smooooth Member

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    Did you replaced all 4 - or just what was needed??

    Reason for asking is that I only need 1

    Thank You

    Stephen
     
    Smooooth, Apr 17, 2011
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  10. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    They're not for the Hitachis.

    Or smaller Mikunis.

    Yet.
     
    bigfitz52, Apr 17, 2011
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  11. Smooooth

    Smooooth Member

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    Smooooth, Apr 17, 2011
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  12. jbmindustries

    jbmindustries New Member

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    As the operator of JBM Industries, I have been asked to reply about the diapragms we are making. We have been manufacturing the diaphragms for Mikuni BS38 carburetors for over a year now. These were used on Yamaha 650, Kawasaki KZ750, and many other motorcycles.
    We are now making diaphragms for some Hitachi carburetors used on Virago, Seca, and Maxim models.
    My problem is that I make parts, but don't know very much about the motorcycles that they fit. Folks wanting diaphragms should measure the goove diameter with a caliper to see how many millimeters the diameter is.
    Right now JBM makes 9 sizes for older motorcycles. Mikuni, Keihin, and Hitachi. People with questions should visit the JBM web site. www.jbmindustries.com. We do recommend you replace all diaphragms at once, rather that just one. We use real high quality rubber that should run your bike another 30 years. I don't plan on making more tooling this summer as things are getting too complicated. You may also find JBM parts on Ebay at times, but they cost a bit more because of Ebay fees.
     
    jbmindustries, Apr 18, 2011
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  13. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The XJ550s used Mikuni BS28s. I'll measure one later today and post; it would be great if you have one available that fits that carb too.

    The Hitachi availability will be good news to a large number of folks on this forum, myself included (I also have a 650 with Hitachis.)

    Keep up the good work. This is a long-needed solution.
     
    bigfitz52, Apr 18, 2011
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  14. jbmindustries

    jbmindustries New Member

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    I think we make the diaphragm to fit the Hitachi used on the XJ550. Look and see if it measures 68mm on the OD.
     
    jbmindustries, Apr 18, 2011
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  15. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The XJ550s didn't use Hitachis. Mikuni BS28.
     
    bigfitz52, Apr 18, 2011
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  16. jbmindustries

    jbmindustries New Member

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    If your bike has Mikuni, it would be a 73mm diameter or a 70 mm I think. Those are the only two we made for around that year.
    You see my problem. I have parts but don't know what fits. I don't even know how many cylinders it has.
     
    jbmindustries, Apr 18, 2011
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  17. TIMEtoRIDE

    TIMEtoRIDE Active Member

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    Welcome to the site JBM !!
     
    TIMEtoRIDE, Apr 18, 2011
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  18. Metal_Bob

    Metal_Bob Active Member

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    I could possibly trade you a full rack of XJ750 4x carbs (dirty) for full set of 4x diaphragms that fit :wink: (Then you'd have a size sample and a set for assembly pictures).

    (I forget what brand/size they are)
     
    Metal_Bob, Apr 18, 2011
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  19. jbmindustries

    jbmindustries New Member

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    Re: Aftermarket CV carb diaphragm replacements - anyone trie

    All I really need would be one carb body and slide. I really think the Maxim has Hitachi carbs, and I have made that mold. 68mm diameter. I usually design the mold, and send back the carb with new diaphragms for the donor that lets me measure it. Pretty sure I got that one. I have a list here that someone in Germany made, ( from experience? ) for different carbs on Yamaha. Carbs might be different in Germany, so I am not sure how much good it does me.
     
    jbmindustries, Apr 18, 2011
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  20. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The XJ550s, both Maxim and Seca, have Mikuni BS28s. (They're 4-cylinder bikes, like the bigger XJs, but came with Mikuni carbs.)

    Most all of the 650/750 series, Maxim and Seca, have Hitachis, not 100% sure of the size, but I think they're 32's.

    The 650 Seca Turbo (only) has "pressurized" type Mikunis, because of the turbocharger.

    The Seca 900 has larger Mikunis, not sure of the size.
     
    bigfitz52, Apr 18, 2011
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