440ex throttle response problem

[hondaman440]

I'm having a problem with throttle response with my new IMS 440 Kit. It runs great at all rpms, except when i really snap the throttle from a dead idle. It seems to bog out and some times even dies on me. I will go to wheelie and can't even get the front end off the ground, its so bad. I am running a keihin fcr39 pumper carb, big gun full exhaust, K & N filter.
The jetting the kit called for on this carb is 168 to 170 main jet (I'm using 170) 3rd clip on the needle (I'm using 3rd clip) and a 52 Pilot jet (I'm using 52) They said 1 1/4 out on the fuel screw (thats what I have)
Has anyone else had this problem, I just feel stupid I have tried everything and I know this isn't right, I mean I should be able to crank the throttle and have it go shouldn't I?
Please help. Thanx in advance.
Ian

[adeptex]

There will be some hesitation from idle to WOT under no load due to a sudden vacuum loss in the carb. If it does it while riding do this,
Turn the fuel screw out 2.5 to 3 turns. Also, take the cover off the acc pump and see if it has a washer between the diaphragm and spring. If it does, Sudco carbs have it, take the washer out . This will richen the pump shot and most likely cure your problem. Good luck