[taylorcraft]

2004 250X 2008 250R top end
Throttle stumble when opened rapidly from low throttle position sounds opposite of bog almost feels too rich. Throttle can be slowly rolled on no problem higher rpms also don't produce it. It becomes more pronounced as air temp and humidity increase, does not do it when temps go below 65-70 low humidity. I am wondering if overall jetting is too rich at higher temps and humidity. I am running a larger main (162) 42 pilot, low end throttle response is alright if I don't open it rapidly. Engine is not overheating it has a cooling fan.

[Back2-2]

Humidity is air density. Thick air = rich condition.
You may want to go the zip tie mod to take the slack out of a quick throttle twist. You may also be too rich which can cause a hesitation with rapid throttle action requiring the air to catch up with the excess fueling.
You may also want to look into adjusting the A/F screw 1/2 turn either way if you do not know if you are rich or lean.
I have to adjust my A/F screw 1/4 to 1/2 for different times of the year to have perfect fueling.

It can be many things but there are a few off the top of my head for you to try.