K&N Air Filter...

[canyonbreeze]

Put in the rather expensive K&N SU-0008 Air Filter for the GSF-400.  It is less air flow than the foam filter I had before.  I had to lean the mixture a bit to get the acceleration back up off idle.  It's been in about two weeks now and is still running richer than before.  Some soot buildup around the exhaust and still not as much oomph in the throttle response.  I may just go back to the foam and write off the K&N.  Anyone else have a similar experience?

[tomacGTi]

Was always too cheap for the K&N. Sure you didn't over-oil it?

Used the Uni universal green sheet when my factory filter finally packed it in. Flows more than a worn out stock one.

[bandito93]

+1 I used the universal uni green foam. Way cheaper than the K + N with similar performance

[canyonbreeze]

Sure you didn't over-oil it?

It comes pre-oiled.  I didn't add any.

[Chris H]

Interesting, would you put money on the K&N flowing less fuel? i had the head off the VVC for a rebuild and port clean up, on refitting i fitted a K&N and i was expecting the bike to need a main jet increase but i only found the needles needed a lift and the bike flowed the same jet at WOT settings. Same tuning that ive used on other 400's and got quite large increases in the main jet. I assumed the air box to be the main restriction and so never thought to try different filters.
May go back to the stock foam which actually covers a larger area than the K&N and retry.

[canyonbreeze]

I would put money on the K&N flowing less air than the foam filter.

[wantone]

sorry to jump this thread but where in the uk can i get a foam filter the searches ive done locally, have come up unavailable!

[canyonbreeze]

I made my own from quality open cell packing foam sprayed with filter oil.  One inch thick foam sprayed liberally on both sides.  May go back to it.  Used the air box cover as the pattern to cut it.