Whats wrong with my bike? (videos inside)

Grumpyforeskin
I’m in need of great help from y’all. This 125sx has about 15ish hours on it and has ran perfectly fine until this. Then this boggy issue came up and I just can’t figure it out. When I let the bike idle or get into low rpms it’ll make this bog noise when I get on the throttle/goose it. Won’t really do it if I’m already like quarter/half throttle, it’ll rev out just fine. Carb has been cleaned but that’s kind of the end of my mechanic skills, replaced spark plug also even know it still looked fine. Still doing the same shit. What could it be?



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DynoDan22
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775
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Victorville, CA US
DynoDan22 5/31/2019 1:13pm
5/31/2019 1:13pm
Too lean in the air screw and possibly pilot jet. Turn the air screw in clockwise all the way and go out maybe 1/2-3/4 and see if that helps. Make sure you record your air screw setting as is first. It definitely too lean on the pilot circuit causing the "buwaaaap". If you have the air screw less than 1 turn out from fully closed to get the big to go away, bump up one size on the pilot jet and start all over again. Also check float level as the Mikuni carbs have been coming set all over the map from the factory.
captmoto
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Rancho Cucamonga, CA US
captmoto 5/31/2019 9:32pm
5/31/2019 9:32pm
What carb does it have? The Mikuni has an internal o-ring that can give you fits if it fails. It's the main reason people swap it out for a Keihin.

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BR8ES
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1914
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6/3/2018
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Bennett, CO US
BR8ES 6/1/2019 9:10am
6/1/2019 9:10am
Spend 12 dollars and get the jet block o-ring kit from JD.
Grumpyforeskin 6/1/2019 12:41pm
6/1/2019 12:41pm
Appreciate all the help fellas, I adjusted the air screw and it sounds just fine now. Thanks again!
Grumpyforeskin 6/1/2019 12:42pm
6/1/2019 12:42pm
captmoto wrote:
What carb does it have? The Mikuni has an internal o-ring that can give you fits if it fails. It's the main reason people swap it...
What carb does it have? The Mikuni has an internal o-ring that can give you fits if it fails. It's the main reason people swap it out for a Keihin.
Yah I’ve got the Mikuni, seems like nothing but problems with this thing. So I’ve heard anyways

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