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Thread: Need suggestion for ATC70 carb jet

  1. #1
    Join Date
    Dec 2007
    Location
    East Texas
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    39

    Need suggestion for ATC70 carb jet

    I am working on a 1985 ATC 70 and I have it running but not well. It idles well but bogs when you push the throttle.

    It has one of the K&N style air filters from dratv.com and I am thinking that I need to use a different size primary jet in the carb.

    Has anyone else had this experience and what size jet do you recommend?

    Thanks for your help.

  2. #2
    Join Date
    Jan 2003
    Location
    NE Arkansas
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    2,344
    One of mine does that. I put the clamp on filter from dratv on it and a 60 main jet. I need to go up another jet size or 2.

    If you run it with the choke on, it will run fine, won't it. That's the way mine is at least.
    36 yo, Apple geek, married with kids, conservative. If you are a GUN OWNER and not a member of the NRA, SHAME ON YOU! JOIN!

    Gun control is not about guns, it's about CONTROL!

    My Rags
    85 ATC70,85 ATC70,85 ATC110,83 ATC185S,85 ATC250ES,02 400EX,04 Polaris ATP 500
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  3. #3
    Join Date
    Oct 2007
    Location
    Grosse Tete, LA
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    3,440
    yeah, it does, we'll be putting a 65 in it in the next few days, so i'll let you know how that works.

    also probably going to be taking the stock exhaust off and moving to a different pipe.

  4. #4
    Join Date
    Dec 2007
    Location
    East Texas
    --
    39
    I'll try running it with the choke on or at least partially on. That's a good idea.

    I wasn't planning on changing the exhaust. That isn't a requirement is it? I'll be looking for your post regarding the jet.

    Thanks for the suggestions.

  5. #5
    Join Date
    Dec 2007
    Location
    East Texas
    --
    39
    I went out to look. The jet I have in there now is the one that came in the rebuild kit from the local honda dealership. Its' a 58. Both the Honda Parts List book and the Clymer book say that a 60 is the stock jet. Strange.

    So, I'll work my way up. I'll try a 60 first just for grins and then perhaps a 62 and then 65 if need be.

    I wonder why the rebuild kit would have a smaller jet size?

  6. #6
    Join Date
    Jan 2003
    Location
    NE Arkansas
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    2,344
    The TRX's had a 60, the ATC's were 58. Your kit may have been for a TRX.

    Goat, let us know what jet you use, before the exhaust change isf you change it. The jets run, 58, 60, 62, 64, 68, 70.... Surely a 64 would be about right, cause 64 to 68 would be a big jump.
    36 yo, Apple geek, married with kids, conservative. If you are a GUN OWNER and not a member of the NRA, SHAME ON YOU! JOIN!

    Gun control is not about guns, it's about CONTROL!

    My Rags
    85 ATC70,85 ATC70,85 ATC110,83 ATC185S,85 ATC250ES,02 400EX,04 Polaris ATP 500
    Past rags:2000 Scrambler 400, 86 350X, 86 250R, 84 200S, 97 ATK260LQ

  7. #7
    Join Date
    Dec 2007
    Location
    East Texas
    --
    39
    Quote Originally Posted by TravEX View Post
    The TRX's had a 60, the ATC's were 58. Your kit may have been for a TRX.

    Goat, let us know what jet you use, before the exhaust change isf you change it. The jets run, 58, 60, 62, 64, 68, 70.... Surely a 64 would be about right, cause 64 to 68 would be a big jump.
    The kit has a 58 in it, but the books say 60. I'll post my results as well providing I have the proper size jets in my carb bucket.

  8. #8
    Join Date
    Jan 2003
    Location
    NE Arkansas
    --
    2,344
    ok,thanks...
    36 yo, Apple geek, married with kids, conservative. If you are a GUN OWNER and not a member of the NRA, SHAME ON YOU! JOIN!

    Gun control is not about guns, it's about CONTROL!

    My Rags
    85 ATC70,85 ATC70,85 ATC110,83 ATC185S,85 ATC250ES,02 400EX,04 Polaris ATP 500
    Past rags:2000 Scrambler 400, 86 350X, 86 250R, 84 200S, 97 ATK260LQ

  9. #9
    Join Date
    Jan 2003
    Location
    NE Arkansas
    --
    2,344
    Any update on jet size?
    36 yo, Apple geek, married with kids, conservative. If you are a GUN OWNER and not a member of the NRA, SHAME ON YOU! JOIN!

    Gun control is not about guns, it's about CONTROL!

    My Rags
    85 ATC70,85 ATC70,85 ATC110,83 ATC185S,85 ATC250ES,02 400EX,04 Polaris ATP 500
    Past rags:2000 Scrambler 400, 86 350X, 86 250R, 84 200S, 97 ATK260LQ

  10. #10
    Join Date
    Oct 2007
    Location
    Grosse Tete, LA
    --
    3,440
    we have 65s in both of the 70s now. that's with the stock airbox and exhaust. on one it seems to have helped performance, on the other it seems to have hurt.

    personally i think with the K&N and a less restrictive exhaust a 68/72 would give the best performance. the 65 should be perfect for just the K&N

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