I have a 2010 XT660Z.
The round foam air filter in the metal cage that sits under the intake snorkel on my bike has another foam filter insert that sits inside it. Both filters are oiled and it came from the shop like this.
Rang my local Yammy dealer and asked how much for a new one cos l was sick of washing, drying, oiling, drying then refitting all in one night.
They didnt know what l was talking about. Said there is only one foam filter there.
Came home, checked the parts list, it's not there.
Took the offending item out, wrote down the part number, called them and said yes thats the foam filter in a metal cage.
Took it into the shop and showed them.
Ahhhh that one. That one was recalled as it didnt do a very good job and we rebuilt a guys engine uner warranty as he sucked in a gut full of dirt here in Western Australia.
He showed me the replacement which was different again to the metal caged foam filter in my bike.
Here is a pick of both filters. I was trying to source the yellow one.



On the right is a foam filter with a Yamaha part numer 11DE4451UF which (on my bike) is fitted inside the one on the left.
Now here's the real twist.
The one the dealer showed me was different again. Much the same as the one on the left but with a big wide foam lip like the one on the right.
Any thoughts on whats going on.
I asked how much for the replacement,free if i bought my bike there or $64 if l didn't.
Now the outside filter is nice and clean cos the yellow foam one catches most of the dirt and dust.
Will be fitting a stage one DNA in the near future but would really like to get to the bottom of what is going on here.
Then today while stuck in traffic in the heat my thermo fan comes on. Sounded like a blender full of gravel. Guess ld better get that sorted quick smart.

Rod.

* Tim Tam mug is representational for size only and forms no part of the air filtering on this or any other Yamaha product.
** Tim Tam mug does however provide relief for many ailments including the very common "Ahh **** l dropped the bloody spring/washer/screw and cant find it" problem which is a common ailment late at night in poor light.