Carb issues with 07 kx250f

Ok guys,

I know that this issue has been discussed ad nauseam but I cannot seem to get an answer/fix to this carb(?) problem. HELP.

On the stand, or hammering the throttle out of a corner, there is a huge flat spot on the acceleration. On the stand it is a big enough issue to stall the bike if the throttle is held wide open. If at an idle, and a high idle I will add, hammer down, hold, bike dies. Another issue that I just though of, when revving (without a load) it takes a few seconds for the idle to drop completely down. it will drop but not all the way, then after a few seconds it will drop the rest of the way. Kinda reminds me of a vacuum leak, or a sticking cable. But I don't think it has a vacuum leak. Ii put on a Boysen QS3 in hopes of fixing. Did not help.

Bike runs great otherwise, but I'm afraid it's going to fail me a just the wrong time, such as in the air.

Any suggestions?

No one nails the throttle on the stand, there is no point in that other than to annoy people.

No one rides at idle, then nails the throttle.

You AP needs adjusting. You do not need a QS3 (unless you want to spend money and not fix the problem).

How to eliminate the 'Bog'

The hanging idle can be caused by a need to slightly open the fuel screw and/or drop the idle speed a tiny bit.

Nailing the throttle on the stand to test. Similar to what one might do on the start line prior to the start.

You are correct in that one would not nail the throttle while riding at idle. That would be an oversimplification of the problem. But one would nail the throttle from idle coming out of a corner that required full braking to enter. In addition one may require full throttle hammer in the air to adjust mid-flight trejectory. Thanks for your input. I have adjusted and readjusted. I will now replace the AP diaphram. As I mentioned previously, the bike runs awesome otherwise.

it sound to me that when you gass it the pilot and the accell pump hit at the same time try a 40 pilot, mine bogged out of the corner with a 42 pilot iam running stock jetting with 1 notch leaner on the needle, runs great

Nailing the throttle on the stand to test. Similar to what one might do on the start line prior to the start.

You are correct in that one would not nail the throttle while riding at idle. That would be an oversimplification of the problem. But one would nail the throttle from idle coming out of a corner that required full braking to enter. In addition one may require full throttle hammer in the air to adjust mid-flight trejectory. Thanks for your input. I have adjusted and readjusted. I will now replace the AP diaphram. As I mentioned previously, the bike runs awesome otherwise.

No one at the starting line simply nails it from idle. Nor does the engine return to idle mid jump. Nor does the bike go to idle in a corner. None of that makes any sense. AP is a simple device. No need to over complicate it.

it sound to me that when you gass it the pilot and the accell pump hit at the same time try a 40 pilot, mine bogged out of the corner with a 42 pilot iam running stock jetting with 1 notch leaner on the needle, runs great

Pilot is for idle only, the effect the pilot has diminishes as you leave idle. And the needle and main are for steady stae. The AP is for accelerating.

Thanks for the input. I'm going to replace the AP diaphram next. If that doesn't work I'll give your suggestion a try.

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