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Thread: 1985 ATC 70 Carburetor Keeps Flooding! NEED ADVICE!

  1. #1
    Join Date
    Feb 2017
    Location
    Downers Grove, IL
    --
    6

    Question 1985 ATC 70 Carburetor Keeps Flooding! NEED ADVICE!

    Help needed! I recently rebuilt the carburetor on my ATC 70 and now every time I add gas to the tank and open the petcock the carburetor floods and fuel comes out of the overflow tube (red arrow, image #1) and the other day it flooded so bad it came out of the top vacuum tube (blue arrow, image #2) and through the air filter compartment soaking the filter. The carburetor was rebuilt using the Freedom County full carburetor rebuild kit (found on Amazon, image #3), including all new jets, o-rings, and springs etc.. The float in the carburetor is not damaged nor does it have any holes in it to take on gas. It's also plastic and non adjustable. The fuel valve needle is also new and seats perfectly in its port with nothing blocking its way and moves freely up and down along with the float. On top of all this, I tried starting the ATC before the carburetor had the chance to fill up and flood and nothing happened. It seems as though there is no fuel mixture getting into the head. The engine has compression, fresh oil (no gas got into it during flood), and a new spark plug which produces spark. I am completely stumped and have no idea what to try next.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
    Join Date
    Feb 2016
    Location
    Somerset West, South Africa
    --
    105
    The drain screw on the bottom of your carb (left of the red arrow in your pic) needs to be closed all the way, that is not the overflow tube. If it comes out the top (with the drain screw properly closed) your float is either not at the correct level or your needle or seat is not doing it's job. Did you replace the seat or only the needle?
    1983 Honda ATC250R
    1983 Honda ATC200E BIG RED
    1985 Honda ATC250ES BIG RED
    2001 Honda TRX90

  3. #3
    Join Date
    Feb 2017
    Location
    Downers Grove, IL
    --
    6
    I realized last night that the drain screw was not tightened all the way. Once I tightened it, no more gas leaked out. Currently the issue is gas mixture is not getting past the carb and into the cylinder head. I tested spark and compression and still nothing. Also, I replaced the fuel valve needle but not the seat. I didn't know the seat was replaceable.. By needle, do you mean the short/fat one that's attached to the float?

  4. #4
    Join Date
    Feb 2017
    Location
    Downers Grove, IL
    --
    6
    Click image for larger version. 

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ID:	242224 What is this part?

  5. #5
    Join Date
    Apr 2017
    Location
    South of France
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    31
    It's the needle jet
    1986 Honda ATC 125M
    1986 Honda ATC 125M - in restoration
    1986 Honda ATC 70 with Lifan 107 - restored
    1979 Yamaha DT 125 MX

  6. #6
    Join Date
    Feb 2017
    Location
    Downers Grove, IL
    --
    6
    Quote Originally Posted by Henrii View Post
    It's the needle jet
    Where does that go on the carb?

  7. #7
    Join Date
    Apr 2017
    Location
    South of France
    --
    31
    In the center with the main jet :
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    Last edited by Henrii; 04-21-2017 at 02:43 AM.
    1986 Honda ATC 125M
    1986 Honda ATC 125M - in restoration
    1986 Honda ATC 70 with Lifan 107 - restored
    1979 Yamaha DT 125 MX

  8. #8
    Join Date
    Feb 2016
    Location
    Somerset West, South Africa
    --
    105
    By needle I mean fuel valve yes (the short fat thing with black cone at the end) .... the seat or in some cases known as needle jet can be replaced yes if you know how. Easy if you have done it a few times and have the correct tools to extract the old one and press the new one in. You always get a replacement with these carb kits.
    I would rather suggest not trying to get it out on this carb (always better to practice on old chinese carbs first) ... these hardly ever need to be replaced anyway, I would suggest rather giving it a good clean, how you do this is: cut a earbud in half, put in your cordless drill, dip the tip of the earbud in metal polish, and gently run it on the seat until it has a mirror shine ... you will probably go through about 5 earbuds before its clean. Is your air/fuel mix screw setting correct? 1 & 1/2 turns outwards from soft stop?
    1983 Honda ATC250R
    1983 Honda ATC200E BIG RED
    1985 Honda ATC250ES BIG RED
    2001 Honda TRX90

  9. #9
    Join Date
    Feb 2017
    Location
    Downers Grove, IL
    --
    6
    Quote Originally Posted by Henrii View Post
    In the center with the main jet :
    Click image for larger version. 

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    Thank you for the images. This definitely looks like the part... So the part in my image (needle jet) Click image for larger version. 

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ID:	242254circled in red goes in first, then the main jet holder, and finally the main jet on top?

  10. #10
    Join Date
    Mar 2010
    Location
    Saint Louis, Mo
    --
    4,127
    Yes, and it's pressed into the carb. You need a brass punch to knock it out. Then you can use the main jet holder to press it back in. I don't believe you can replace the needle seat on that carb. Are you sure you have nothing blocking the needle valve?
    Feedback for yaegerb: Click Here

    Need something blasted or polished or both? Send me a PM

  11. #11
    Join Date
    Feb 2017
    Location
    Downers Grove, IL
    --
    6
    Quote Originally Posted by yaegerb View Post
    Yes, and it's pressed into the carb. You need a brass punch to knock it out. Then you can use the main jet holder to press it back in. I don't believe you can replace the needle seat on that carb. Are you sure you have nothing blocking the needle valve?
    I figured it out! Looks like my throttle was set too high and my pilot screw was set wrong as well. I was also able to replaced the needle jet. After all that, started on the first pull.

  12. #12
    Join Date
    Feb 2016
    Location
    Somerset West, South Africa
    --
    105
    Glad you got it figured out.
    1983 Honda ATC250R
    1983 Honda ATC200E BIG RED
    1985 Honda ATC250ES BIG RED
    2001 Honda TRX90

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