K&N pre-filter

[KW]

I’m pulling my tank tomorrow and cleaning the K&N filter. Should I leave the foam pre-filter off?  Just wondering. When I installed it a couple years ago I never even considered leaving it off, but I’ve read some comments here where people do. So, what’s the group consensus here?

[Zorba]

leave it off, no harm and the bike will breath better!
Mines been off for years now!

[R J]

Also, get a longer front tank bolt and add a spacer in there to raise the front of the tank up.

NO pre-filter and raised tank, MGM breathes real good........

BigBF also sells these kits.

http://www.bigbf.com

[Jess from VA]

Unless you have rejetted, you should leave the prefilter in place.  It is called for in the application for a stock Valk, and leaving it off can lean out your bike (some maybe not, but some definitely so).  Leaving it in does not restrict necessary air to the bike or restrict horsepower.  If it is also dirty, clean it as well as the K & N filter.

[John Schmidt]

Jerry, I'm in the "no prefilter" camp. The K&N was on when I bought the bike nearly 8 yrs. ago, didn't even know it came with a prefilter until some time later when it was mentioned on here. I never rejetted, never had the need after looking at the plugs. I did go to larger slow jets a couple years ago when the dumb doorknobs in Tallahassee forced everyone to start using corn liquor in their gas tanks. Mileage dropped 2-3 mpg...but they still think we're using less gas. Anyway....I had run the K&N for about five years prior with no trouble, and aftermarket pipes.

[dago mooserider]

I did a de-smog and k&n (no prefilter) a few months back. I think I was already a little lean from the factory and this seems to have made it (very) slightly worse. Plugs are a little to clean but other than exhaust popping no ill effects. I'm waiting until my exhaust is done to rejet.

[Tundra]

I've run it both ways and now keep it without the pre-filter. (actually can't tell either way) Everyones always coming up with tricks to "get more air" anyway. My plugs look good.

[KW]

Thanks guys for the feedback. I pulled the tank this afternoon. The condition of the pre-filter has dictated which way I go. It (pre-filter) had caught quite a bit of garbage on the end where the air tunnel opens over carb intakes. There was a 1/2" strip, a 1/4 - 3/8" tall, build up up of dirt, small leafs and bugs on that end of the foam filter.  I was surprised. It hasn't been that many miles since I cleaned it. Most of my miles - almost all of them - are at 60-65 mph on two lane highways and open backroads. Maybe that explains it? Go figure. I was all jazzed up to peel that thing off and see if there was any difference. Oh well . . . .