i got an 04 ltz 400 ltd ed i bought it off an old friend the motor was gone so i sent it away to get fixed i got it back and put it all back to geather i put a yoshimura slip-on and a FMF power-up jet kit with a DJ150 in it and have the fuel mixture screw at 3.5 turns out and it will start up, but it idles for a sec and stalls out it keeps diong that i'm not sure what it could be if anyone has any awnser please let me know thanks

 

Dyno-jet jet kit is the way to go, specially to fine tune your bike, if your gonna do anything with the pipe at least get a slip on either HMF or Yoshi RS-3 slipon, both of those work good and are pretty cheap, if not just leave your stock pipe alone, those "power caps" are most likely a fail gimmick like the boost bottles and torque stuffers are, if your getting a cap for looks then thats ok, but just dnt be suprised if u dont notice a difference, you honestly wont need mods to be the fastest of those two people you ride with, seat time is where its at, and its free, lol.