jsut a jet question

[kfx400isdashiz]

ok i have an 03 kfx400 i bought it used. the guy who had it before me tore out all the packing and spark arrestor from the stock pipe and threw in a bigger jet. i am now going to put in the drz e base head gasget for added compression and i boguht a used LRD pro 4 series slip on pipe from ebay. will i need to get a bigger jet? or rejet?

[indyZrider]

there's alot of if's there. are you going to take the airbox lid off? are you going to add a k&n filter? I would. but generally if you just add the slip on then your jetting shouldnt really be too off but if you want to make that thing roar then add a pro design k&n kit--one with the billet base plate- and leave your lid off and rejet that sucker and it will be a different bike. you might want to get an adjustable needle to. you can get one if you just spend 40 bucks on a dyno jet kit with all the jets you will need.

besides what size jet do you already have in it? what about the pilot jet also? is it stock or bigger?

[kfx400isdashiz]

i already got a k&n but do not wish to remove airbox lid. pilot jet is stock no spark arrestor in either pipe just by lookin it looks like the LRD is ognna alow alot more airflow. what would you do

[indyZrider]

if you leave the lid on you wont need as big of a jet. you could always get an EHS lid. it lets air through but keeps most of the dirt and water out. also you can take the tip of the snorkle off. there is going to be alot of trial and error so be patient. mine has a 155 dj main jet, a 25 pilot jet, its on the 3rd clip on the dj adjustable needle and i have the snorkle tip removed with the ehs lid. if your going to run with the lid on i would start with a 142 or around there. the thing is if you decide to take the lid off later you will have to rejet again. you could always call lrd or check their website and see what they recommend.