running problem

[400ex45]

my dad got a 05 450r and we put a new piston in it and piped it and rejeted when u get up above 5000 rpms around there it starts 2 sputter or miss or act like the rev limiter is on and i have no clue what it is

things we check is timing, valve clearance, played all around with jetting, switch cdi with good one, checked wiring

i have no clue what is wrong and is wondering if anyone else ever had this problem

[pro-rider46]

mine has the same exact problem but it dont have the same mods you do, but i think it is a bad stator. i plan on taking it to the dealership here soon and if i am lucky it will be covered under warranty but it might not because i have that new cam in it. if i find out what it is i will post it back here.

[pro-rider46]

do you have a after market cdi on it because i think that is what screwed it over for me.

[gixxerfreak01]

did you put a 50 pilot jet or get a hrc needle i dont know maybe dirty carb thats what my problem was

[400ex45]

i have clean the carb twice and i know it is not the pilot because bottom end is great i might try to play with the needle but i dont think it will help. and i have stock cdi.