I got a 2001 300ex all stock except for the K&N filter I installed yesterday. I did not get the whole jet as my buddy got the who shebang for his warrior and has many jets left over. I read on a site that I should run a #130 main and drill a 2" hole in the air lid. I installed the jet but did not want to drill the lid, the bike runs like crap now, I need to know "FROM EXPERIENCE" how to set up my carb ie. main jet size, needle position, pilot jet, etc. I live in W. Kentucky not sure of the alt. but It is not in the mountains.The main jets were the round type not the hex type that came out of it.

 

when I put the pipe on my bike I bought the K&N atv jet kit. it gave instructions on everything you need to know.

if you just have a filter I suggest you get the stage 1/stage 2 (one package) jet kit. should run you about $45.