I have a 02 warrior with a cobra pipe and just got a K&N air filter will I need to put in a jet kit I well be running it with the air box lid on

 

i would think that if you are adding air { k&n } getting rid of burnt gas faster { pipe } then you need to add more gas..just a thought. i did mine but the day i went out to test it the piston fell apart.. not becouse of the mods but the rod berings were shot and that coused the piston skirt to go when i took it apart 1/2 the rod berings were gone and a lot of meatle powder in the case

 

It will run fine the way it is but you could go up 5 on your jets and see if you like that better?

 

Deffinatly Re-jet. Befor you even run it, i would go up 3 sizes and then tune it from their. Maybee even 5. Its better to start out rich then lean..good luck.