What should I do???

[Fast-n-Furious]

I just got my FMF Power Core IV SA today and i put it right on. My 400 doesn't want to idle with it on but if you just touch the throttle a little it will run good and move in first. When you go to give it more power it sputters so i think it needs to be getting more gas right. So i have to rejet. Should i purchase a jet kit for 44 bucks? Will that gurantee that it will run right after i put it in? OR Should i go down to the shop and buy the jets that FMF reccomends (40 pilot and 150-152 main) and hope it runs right when i put them in? Any other suggestions?Thanks.
Ryan-

i'd go to the shop and get what FMF recommends and 1 size up, since you don't want to run lean. i'd put on the bigger jet, then move down to the smaller ones

[Punk13rym]

check the gas mixture screw. you may need to turn it a little to get more gas flowing into the carb. when i installed my jet kit it said ture it 2.5 or so turns out from all the way in.

[Fast-n-Furious]

ok ill go pick up the jets and turn the fuel mixture screw and see how she runs then thanks for the advice.

[kicken250x]

mine is like 5 or 7 or something out from all the way in i think it is time to go up 1 or 2 sizes what yall think lol?