Jets for K+n

[AtvMxRider]

I'm going to install a K+N filter as soon as get my 400 broken in what size jets should I use. It is bone stock and I'm not sure what size jets are in it right now does anybody know what comes in them stock?

[phatswinn]

after you put it on, put a new plug in and go for a 3 hour ride, then tell us wht color the plug is, if its lighter that a coffee brown then you need to go up one size on the main jet and if its darker than a coffee brown you should go down one size but i found that the quads come jetted rich from the store and the k&n made up for that and made my quad run right

[AtvMxRider]

should I wait until I get it broken in first or can I can install it now.

[eldoexrider01]

if i was u..id break it in stock. then do mods. but ive never seen a 4wheeler broke in wit mods in it so i couldnt tell ya what would happen. jus to be safe id go stock for alil bit

[AtvMxRider]

Thanks!

[Teufel]

Put the K&N on and go ridin, all things considered you probably won't have to change the jets. They are intentionally jetted a little on the rich side from the factory so the filter will help to bring it back..

Just my opinion

[racer_ex55]

Actually most fourstrokes are jetted lean from the factory to help them pass emmissions. IF you install the filter you should go up at least one size on the main. you can go up a size or two from bone stock anyways so with the filter you could go up one size easily. try a 150, or 155. Also try putting some holes in the airbox lid or if you don't run in wet or really muddy conditions take it off entirely.