Am i suposse to put out the k&N

[jordanhudon]

I would like to ride my atv this winter but on my 300 ex i got a K&n filtrer and i would like to know if i need to put it out or it is not a problem ?!

you will be fine...jetting may end up a little off, but it will be ok...

i have run my 400ex and 300ex with k&n filters in the winter with no problems

[bwamos]

Been running K&N's for years (almost 9). Summer, Winter, Rain, Shine, Mud, Sand, Dirt, Snow, Ice, Water, etc with no problems. (I run with an outerwears, no lid, drain plug removed).

In the winter when it's like 40deg and below you probably want to kick your mainjet up one size. Cold air is more dense so you have more oxygen per cubic ft an it makes you run a bit leaner.