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butterfly valves sticking?

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  • butterfly valves sticking?

    Hello and welcome to the saga of my carb cleaning.

    My idle was a little choppy, so last week I decided I would just clean the carbs and pop 'em back in. I balanced the floats and bread-tie pre-synced them. Now the bike won't idle below 2.5K rpm.

    I pulled the idle screw back til it came out and no drop in rpms. So I released the throttle cable from its carb mount and snapped the butterfly valves and the rpm dropped, so it seems these valves are sticking, ie. not relaxing to a closed state when there's no throttle. Re-synced under a very bright light, and checked both sides of each valve. One seems ever-so-slightly warped/bent (both sides don't close the same), but its so slight (maybe 1/16th the width of the bread tie) that I don't think this is the issue.

    I haven't messed with the mixing valves or the jets (aside from cleaning the latter).

    So I swabbed the rims of these valves with q-tips and gasoline and cleaned their contact point to the venturi, and they're still sticking. The sticking is not terribly obvious when the carb is out of the engine, but its the only conclusion I've been able to come to with the evidence presented.

    Any suggestions? The weather has been great so she's probably just crying herself to sleep every night out in the garage.
    '79 XS1100F

  • #2
    dsweeney,

    The bread tie sync only gets you in the neighborhood. You know you're in the neighborhood 'cause it runs. You need to do a final vacuum sync and idle mixture adjustment.

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