rough start

[anderson3064]

ok my 03 400ex is cold natured, also after it runs a bit it like to back fire when punching it and then getting out of the gas, it has an pro circuit t-4 pipe and thats it, rest is stock

[Mechanixx]

You did jet it correct?If not youll need to jet it for your pipe.Cold start blues !!!! (http://www.exriders.com/vbb/showthread.php?s=&threadid=221742)
Jetting !!!! (http://www.hmfengineering.com/forums/showthread.php?t=497)
This will help if you havent jetted it :p

[Old Head]

Yea check your jetting and if thats ok back your fuel screw out 1/4 turn at a time but no more than 3 1/2 out till it stops.

[anderson3064]

thanks, this is my first four stoke and its a whole new world

[anderson3064]

hey head, read in your sig you got the powerbomb header. notice any difference performance wise with that mod