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Keihin butterfly carb

Discussion in 'Motorcycle Tech Talk' started by joshbob, Nov 26, 2010.

  1. joshbob

    joshbob Well-Known Member

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    My Keihin butterfly carb has the serial # B81A PL05. Does this mean that the carb was manufactured in 1981? It came bolted to a '77 shovelhead motor I recently acquired, but the Harley Manual ('70 thru early '78) shows a slightly different Keihin carb. What do the serial numbers mean? The carb I have has an idle mixture screw.
    Last edited: Nov 26, 2010
    joshbob, Nov 26, 2010
    #1
  3. chucktx

    chucktx Moderator Staff Member

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    maybe ken has an answer....i dont do serial numbers!! lol
    chucktx, Nov 26, 2010
    #2
  4. kenfuzed

    kenfuzed Administrator Staff Member

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    Wish I could help you Josh but the serial number on most of those carbs were assigned by Keihin rather than Harley. I recall having a B83A number on a 79 Ironhead so I don't believe the "81" to be a date... that would be too easy.

    I can tell you that the Keihin butterfly carb is one of my least favorite carburetors and I could probably fill a dumpster with as many as I've tossed away in exchange for a newer CV carburetor (90-06). Shovels and Ironheads sign when fitted with a CV 40 carb.
    kenfuzed, Nov 26, 2010
    #3
  5. joshbob

    joshbob Well-Known Member

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    Ken,
    Thanks for the quick reply. I've been told by others to trash the Keihin and get the CV version. I just hate to throw things away if there's a chance to fix them, and as far as I know, there's nothing wrong with it. My motor came rebuilt from Rob's Used Harley Parts in Weston, Va., but he said he didn't know if the carb had been rebuilt. I won't really know how it will function until I get my tranny & primary hooked up and kick the 'ol thang to life. In the meantime, I will take the Keihin apart and look it over. Why are people so down on the Keihin butterfly? It worked fine for me in the 70's. I'm 67 now, and haven't ridden in a long while. My bobber project is an attempt to get these ol' knees in the breeze for a few more years (God willing) before I get too old to ride anymore. Most everything is retro on the machine (70's or earlier), and I'm not into high performance, flames, skulls, maltese crosses or F*** U tail light lenses; just a reliable, clean scoot that has attitude enough without all the add ons.
    I expect it's going to take some time to look over your entire web site, but what I've seen so far is excellent.
    joshbob
    joshbob, Nov 27, 2010
    #4
  6. JohnnyBiker

    JohnnyBiker Well-Known Member

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    :worthless:
    JohnnyBiker, Nov 27, 2010
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  7. sarge7

    sarge7 New Member

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    The Kliehn with butterfly is a lot like the the old linkharts - I've had both and spent more cussin at them than I do my OL - and she works a hell of better then either one of those carbs. - although she is a little hard to kick in the morning. :roflmao::roflmao:
    sarge7, Nov 27, 2010
    #6
  8. joshbob

    joshbob Well-Known Member

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    Chucktx,
    Thanks for the reply. I'm beginning to think the numbers don't mean much at all. I was trying to find out what year the ol' thang was manufactured, but that doesn't seem to matter much, either. Everybody sez to junk the butterfly and go with a CV. Gonna go with the butterfly until further notice . . .
    joshbob, Nov 28, 2010
    #7
  9. JohnnyBiker

    JohnnyBiker Well-Known Member

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    You could call Harley themselves and ask them. I have had good luck with this.
    JohnnyBiker, Nov 28, 2010
    #8
  10. chucktx

    chucktx Moderator Staff Member

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    i have messed with them. most of the time they were a fairly good carb. but, since the cv came out, and their low cost, and ease of tuning, and they stay tuned and self adjust for altitudes.....they win hands down!! hope ya get yours tuned to your satisfaction, but if not, spend 50 bucks and get ya one, ya wont reget it. have fun and stay safe!!
    chucktx, Nov 28, 2010
    #9

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