Ok, My 99 Sportsman 500 was leaking fuel from the drain tube on the carb. i replaced the needle and seat and cleaned everything out. the leak is gone, and i set the float height right at 0.51" according to the manual.
it does not leak, and runs perfect at idle BUT,

if you hold the throttle about 1/8'' past idle and leave it there, about 3 seconds later it starts gargling/acting like its going to die. if you jam on the gas from there, it shoots a puff of black smoke and runs fine at 3/4 and full throttle. it is just acting badly a little past idle up to half throttle, if you hold the gas at that position.
i tried pushing the tang in more and pulled it out until it was flat with the rest of the metal it is attached to, but it seems to still act up.

any ideas?? i have the carb pulled right now awaiting responses. thanks!!!

 

Did this just happen after you fixed the needle and seat? Bet you didnt like the price of those little parts!! I go to atvworks.com to get the needle and seat for about $20.

 

Also make sure your pilot jet is cleaned out real good. I let mine sit in Coke for 15min then spray it with carb cleaner. Those jets get junk in them real easy.

 

got my needle and seat from the dealer for $28 out the door.
i will go clean the pilot but any ideas what else it could be?

 

Did this problem just start after you fixed the needle and seat? That is a good price from your dealer, mine was $40 for a needle and seat, but that was on an 2004.5 model. Also check the boot that goes from the air box to the carb and the carb to the engine (they can crack or split or dry rot.)

 

well i think i got it fixed. i will find out 100% Sat. on the ride.
come to find out, the needle and seat did need to be replaced but the problem causing the spitting and sputtering was from a friend that had previously taken the carb apart for me.
i finally got tired of not knowing what was wrong, so i got the manual out and gutted the carb to clean everything out. i found the jet needle had been placed behind the diaphragm wrong somehow. once i cleaned everything and put it back in correctly, it fired right up and no sputter....so far. thanks for the advice