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  • Carb idle screw question

    I recently cleaned my carbs. I noticed that the idle screw is not centered on the throttle piece that it contacts. Is this normal and/or benign?

    Thinking that the screw+bracket was at fault, I purchased another from FleaBay. Exactly the same off-center location.

    82 XJ1100 - sold
    96 Honda Magna 750 - Girlfriend's bike
    2000 ZRX1100 - sold
    2003 FJR1300 - Silver rocket

  • #2
    Originally posted by HalfCentury View Post
    I recently cleaned my carbs. I noticed that the idle screw is not centered on the throttle piece that it contacts. Is this normal and/or benign?

    Thinking that the screw+bracket was at fault, I purchased another from FleaBay. Exactly the same off-center location.

    I would imagine leaving the screw in and carefully rotating mount bracket with a pair of pliers a bit, compensating for the pre-tapped hole would re-align it.
    Last edited by motoman; 05-28-2016, 05:23 PM.
    81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

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    • #3
      I would just leave it! Trying to move that the 50 thou isn't worth the risk of messing it up beyond repair(FUBAR in the army). All the screw needs is to keep the throttle opened a bit, and it does that.
      Ray Matteis
      KE6NHG
      XS1100 E '78 (winter project)
      XS1100 SF Bob Jones worked on it!

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      • #4
        Originally posted by DiverRay View Post
        I would just leave it! Trying to move that the 50 thou isn't worth the risk of messing it up beyond repair(FUBAR in the army). All the screw needs is to keep the throttle opened a bit, and it does that.
        Point taken. I am still wondering if this is common. ???

        After more inspection, there is a washer on the throttle shaft spring for the carb above this screw. I wonder if another washer could be added to move the contact point over the thickness of the washer.

        Lastly, I could use the second screw+bracket for an experiment of hand filing the mounting holes over 50 thou.

        Yeah, and I can also leave it alone. It has probably been like this since the last time that the carbs were disassembled/assembled which could be the original manufacture date in 1981.

        Thanks for the response.
        82 XJ1100 - sold
        96 Honda Magna 750 - Girlfriend's bike
        2000 ZRX1100 - sold
        2003 FJR1300 - Silver rocket

        Comment


        • #5
          Originally posted by HalfCentury View Post
          Point taken. I am still wondering if this is common. ???

          After more inspection, there is a washer on the throttle shaft spring for the carb above this screw. I wonder if another washer could be added to move the contact point over the thickness of the washer.

          Lastly, I could use the second screw+bracket for an experiment of hand filing the mounting holes over 50 thou.

          Yeah, and I can also leave it alone. It has probably been like this since the last time that the carbs were disassembled/assembled which could be the original manufacture date in 1981.

          Thanks for the response.
          Fixed location, so doubtful.
          Last option would likely be the best.
          81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

          Comment


          • #6
            I evaluated the action as-is. My concern is that when the throttle is release for engine breaking, this screw receives the force of the throttle shaft springs.

            I did not want to bend the bracket. That would cause the screw to not be parallel to the arm that it pushes against. I tested for being parallel by running the screw all the way as far as it can go. It is parallel as-is.

            Having an extra screw+bracket to experiment with, I pulled out some round files and went to town on the mounting holes to transform the holes into slots allowing side-to-side adjustment of the idle screw position.

            The files were painfully slow. I ended up chucking an appropriate sized drill bit into the drill press and using that to ream the holes into slots. Eventually I was able to position the bracket to center the idle screw. i finished up with two hex head bolts and some washers to make sure that the bracket is firmly affixed in place.

            82 XJ1100 - sold
            96 Honda Magna 750 - Girlfriend's bike
            2000 ZRX1100 - sold
            2003 FJR1300 - Silver rocket

            Comment

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