Air fuel mixture screw issues.

Discussion in 'Carb/Tuning' started by Osiris, Jul 10, 2018.

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  1. Jul 10, 2018 #1

    Osiris

    Osiris

    Osiris

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    I ordered replacement screw due to a stripped screw right rear carb. The carb was a bit rich and I could not adjust screw. When taking the old screw out it was very very tight. I see why it was stripped in the 1st place. When I look inside the carb I see no obstruction, but the the screw will not screw in enough the tune right. (Still rich) Even with the new screw turning it in is very tough. I don't believe I'm bottoming out. The screw just won't screw in. When I removed the spring and washer and o-ring the screw went in with ease. I could feel it bottom out and it turned with little effort.
    All the other carbs adjust just fine. Anybody else ever have a similar situation? Any Ideas what might be going on? Any insight would be greatly appreciated.

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  2. Jul 11, 2018 #2

    lilredrooster

    lilredrooster

    lilredrooster

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    Is the new screw set you bought a yamaha factory part?

    Just a thought, wonder if there is an old original o-ring and washer stuck in the very bottom of the hole or some debris etc (very hard to see into the base), if so, you are maybe then adding a second o-ring & washer which is not allowing the screw to go all the way in?

    Had trouble in the past removing the old washers and hard crusty o-rings.....

    You could try it with the screw and the spring only and see if it goes all the way in then maybe try it....
     
  3. Jul 12, 2018 #3

    Osiris

    Osiris

    Osiris

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    The replacement screws are Yamaha screws. I too thought there may be a stuck o-ring. I have not found one though. I think I may try the screw with just the spring and see what happens. Thanks for the input.
     
  4. Jul 12, 2018 #4

    lilredrooster

    lilredrooster

    lilredrooster

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    Good Luck mate, I feel your pain, I found a magnifying glass helpful to see right down there and of course a torch/light, I used a piece of fine stainless steel lock-wire, shaped a sort of tiny 80/90 degree hook on the end to get inside the Ins/Dia of the o-ring & washer, very very hard to tell that the bottom is clear, I ended up taking the carbs off to get it cleaned out....

    I am thinking if you put your new screw with spring in and try that first, if you can feel the screw compress the spring and the screw seat at the end ok, then it points to being something down there, you could then fire the bike up and try to see if it functions ok? You then have the option to leave as is or go back in and fish it out.....

    Best of Luck Mate....
     

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