In my other bikes i've ran k&n air filters and loved it.
But my f4i is stock and most people on here would say leave it that way, it will run better.
Well my stock air filter is turning black, disgusting, and about that time for a replacement. Anybody using k&n filters in their f4i's ? Will it provide too much air for idle and cause the mixture to be all funny? I've also heard of covering one of the stacks, what is that all about?

 

k&n filters suck. the actually let larger particles through than a normal filter (based on micron size). it will in no way give you more power. tested on dyno's time and time again. you have to alter your exhaust and then remap the ecu to see a difference. they are a pain in teh butt the oil and junk too. you can get an emco filter for around 20$ and they work great.

best stuntbike is one that hasn't been modified. once you change anything with the motor it won't be as smooth or pull as strong.....but it might give you a few extra ponies on top, where we never ride our bikes.

 

ya i agree... dont use KnN on a stuntbike...
i bought a f4i after having a r1 for bout a year..
when i was doin other **** noticed filter was knar dirty so i got a knN and now when im doin idle **** like slow circles an whatnot it has a bog... jus right of idle... an its a pain in the ***...
i am running ducttape over one of the inlets to the airbox an helps alil but im deifently goin to a diffrent filter..
althou it does run better on top end...
but dont really need that

 

ya, i keep one of my inlets taped off on my f4i and that's with a stock filter. gives me that low end and doesn't cause the bike to go lean.

edit: you can actually see the blue painters tape in my avatar. sweet