Found a K&N filter that fits practically identical to the OEM filter size wise. Part Number is RU-3560.  This might be the same one for sale at toobefast.com but I couldn't find a part no. on the website so I just looked up what might fit on K&N's website. Fits perfect in my 2016 800ex.

http://imagizer.imageshack.us/v2/640x480q90/922/xkPafH.jpg

[2015 Z Force 800 53/Trail EPS]

Found a K&N filter that fits practically identical to the OEM filter size wise. Part Number is RU-3560.  This might be the same one for sale at toobefast.com but I couldn't find a part no. on the website so I just looked up what might fit on K&N's website. Fits perfect in my 2016 800ex.

http://imagizer.imageshack.us/v2/640x480q90/922/xkPafH.jpg

Ever sense a K&N filter failed and cracked wide open on a member destroying his engine, we don't use them. You shouldn't either. Only properly oiled dual stage foam filters.

Ever sense a K&N filter failed and cracked wide open on a member destroying his engine, we don't use them. You shouldn't either. Only properly oiled dual stage foam filters.
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I can see that happening as a one off. I've always used K&N's in all my ATV's and never had a problem. I looked at the inside of one of the stock filters and its basically the same material design but with a lot more "cloth" fibers.

http://imageshack.com/a/img923/2930/46T4Rz.jpg

[2015 Z Force 800 53/Trail EPS]

Ever sense a K&N filter failed and cracked wide open on a member destroying his engine, we don't use them. You shouldn't either. Only properly oiled dual stage foam filters.

I can see that happening as a one off. I've always used K&N's in all my ATV's and never had a problem. I looked at the inside of one of the stock filters and its basically the same material design but with a lot more "cloth" fibers.

http://imageshack.com/a/img923/2930/46T4Rz.jpg
[/quote]

On this guy's what happened was it got packed with dirt, enough that it became restricted. Then the intake pulsations started flexing the wire until fatigue weakened it and pulled inward opening up and letting everything in. There's a photo around here somewhere.

[2015 Z Force 800 53/Trail EPS]

Here, let this image soak in a while...lol

http://cfmoto-forum.com/800ex800/warning-about-kn-air-filters/

Avoid a K&N on an off road vehicle at all costs.  They just don't stop the dust.  Go with oiled foam or paper.  I would suggest a UNI or Twin Air.