I rejetted my banshee this weekend for taking the air box lid off and a colder weather.
Mods are:
Air box: adapter plate W/Twin air foam filter W/ foam outerware
FMF Gnarlies
Jetting:
Elevation 300'-600'
Temp 40 to 60 degrees F.
#30 pilots, air screws 2.5 out
Needles stock position (3rd clip down)
#290 mains
I thought #290's might be a tad on the rich side but they were perfect .
Did a plug chop, 2mm brown band at the base of the electrode, goes in the band quick no hesitations, pulled hard all the way to the top of 6th in sandy conditions.
I talked with a local yamaha shop when getting a couple of sparkplugs to sacrafice for the plug chop and they said that the Gnarlies, Fatties, and SST's all jet pretty close to the same. With a K&N I'd say you should be pretty close to my settings on the pilot, possible raise the needle one clip, and +4 on the mains which would put you at 330 on the mains. If your colder than 40 deg. then possibly one more size on the main and if your at 1500' ele. or more then minus one size on the main. Whatever you do decide to jet it at, do a plug chop, that is the only reliable method to tell if your jetting is adequate.
If your air screws like to be 2.5 turns out, then I'd drop your pilots to a 27.5. I bet you'll have better throttle response and better low end...You'll also have more adjustment for summer..you should turn the screws in for winter and out for summer...I find the best pilot size is when the air screws like to be between 1-1.5 turns out....good luck