Idle screw does nothing

Discussion in 'Tech Area' started by mtspeeddemon, May 14, 2018.

  1. mtspeeddemon

    mtspeeddemon Member

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    I'm beyond frustrated with OEM carbs! I have two freshly rebuilt, a good engine and can't ride ugh!

    CT70K0 ran ok, rebuilt carb, now it starts but idles way too high. Idle screw does nothing.
    No intake leaks as far as I can tell.
    I am sure the slide and needle are installed correctly.

    The other carb constantly overflows, I think the overflow tube in the bowl is cracked so I have a spare parts carb now :(

    I'm about to offer to buy known working OEM carbs from someone who will test them on a good engine first.

    Now I've discovered the throttle cable is adjustable just above the carb but trying to adjust the idle with that had been hopeless.

    I'm trying to get back into the Trail bike scene.
     
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  3. cjpayne

    cjpayne Well-Known Member

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    There's a small piece in the throttle twist that's easy to install backwards. It slides over the cable sheath, THEN screws on to the end.
    ....and/or the cable sheath isn't setting down into the carb neck fully. I've had those pull out before from putting the handle bars down.
    If you changed the model carb from original or replaced the throttle cable itself, measure the cable lengths to make sure they are the same.
     
  4. kirrbby

    kirrbby Well-Known Member

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    Screenshot_20180514-093633.png
     
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  5. racerx

    racerx Administrator
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    Your fuel overflow most likely indicates that the fuel level is too high, inside the bowl. A bowl swap is an easy way of verifying this...if the other bowl corrects the problem, then you have a crack, as you though. If not, then it's either a float problem (incorrect height, or a leak on one side) or the needle & seat not sealing properly. Neither is difficult to repair.
     
  6. mtspeeddemon

    mtspeeddemon Member

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    Thanks guys. I was really frustrated when I posted and needed a break I guess. I have not revisited this but maybe I'll get it worked out this weekend.
     
  7. CT70_Scotts

    CT70_Scotts Member

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    A thought or a FYI you can buy that cheap repop carb for like 22 on ebay and use the bowl. You can use your stock shut off on it so it still is the correct orientation as the stock. I did this on a K1 as the bowl was so corroded I blew through it with the sand blaster. I will do this on another as I have some stripped screw holes on the shut off side. It's really not a bad piece for the price.
     
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