White Bro's missing

I have a 99 400 ex with a uni filter, and an e series slip on nd a 155 main jet. I have a sligh hesitation at just above idle speed when im just luggin along in a higher gear it sputters and it will eventually stall if no fully warmed up ,when warmed it will still hesitate but it wont stall. Also when i use engine braking there is a stream of pops and backfires,which arent bad but they are there. Is this the pilot jet or fuel screw?

If anyone else had this problem could you please reply.

Thank you for your info.

[tprender]

You are having problems in the low end. The main jet has nothing to do with this. As a starting point try a 45 pilot with the clip in the middle and the air screw about 2 1/2 turns out. This is just a starting point.