K&N Air Filter

[robin]

Do you put the foam pre filter in?

[Bota58]

Hi,most people that I've talked to have left them out especially if they have rejetted the carbs,I've got mine out also.

[Jess from VA]

Yes, it is called for in the Valk application.  

It could cause a lean condition without it, but hundreds here run it with no prefilter so maybe not.  

I always err on the side of protecting my bikes.

Recall the recent discussion about fine particles flowing thu the K & Ns, and how many (like me) go a year or two between tank pulls (and reoiling)?  My prefilter gets pretty dirty, between tank pulls (and I spray it with brake cleaner and stomp on it to clean).

A dusty riding environment is also relevant.

[salty1]

Yes, it is called for in the Valk application.  

It could cause a lean condition without it, but hundreds here run it with no prefilter so maybe not.  

I always err on the side of protecting my bikes.

Recall the recent discussion about fine particles flowing thu the K & Ns, and how many (like me) go a year or two between tank pulls (and reoiling)?  My prefilter gets pretty dirty, between tank pulls (and I spray it with brake cleaner and stomp on it to clean).

A dusty riding environment is also relevant.

+1    I prefer the prefilter because my Valk will run lean and backfire on decel.

[98valk]

K&N lets in a lot of dirt, google the reports/testing even k&ns own testing proves this if one understands the SAE test they use. search for the spicer test.
the oem filter is good for 20-30k miles, (changing at 12k is an industry std since the manufactures do not know what conditions a vehicle will be driven in like the 3k miles oil change only true about 10% of the time) and flows more than enough air to make 100 dyno hp on my bike.
I have over 20k on my oem filter, no change in performance, mpg or plug reading.

[Mildew]

The K&N didn't do anything for my diesel pickup either. Just let more dirt in.

[98valk]

The K&N didn't do anything for my diesel pickup either. Just let more dirt in.

http://home.roadrunner.com/~jbplock/ISO5011/SPICER.htm

actual test showing how bad a K&N is. the K&N is a race track item that shouldn't be used on the street.
www.bobistheoilguy.com  plenty of oil analyisis results of high dirt levels when a K&N or one of the other cotton type filters are used.

[fudgie]

I have mine in.

[Tropic traveler]

I talked to a K&N rep several years ago about the pre-filter. He said that a K&N with the pre-filter flows roughly equal to a stock paper filter.
I have had a K&N with pre-filter in my '97 & it does keep the air clean judging by lack of residue on the inside of the housing. Still do not trust any oiled gauze filter in turbocharged applications.
 

[uturn]

hmmmm y'all got me thinkin that next wrench party i might throw a paper one back in there and see how it runs. i have the bare k&n, i put 38's in for slow jets and all my cool decel backfire went away. maybe the paper will lean it up just enough to reinstal my deceleration alarm?

[bentwrench]

I had a K+N in mine w/o pre filter for 25k miles.At that milage it had picked up less dirt than the stocker did at 10k.So I put an o.e. filter back in.About 12k miles later I sent an oil sample to blackstone along with some fleet samples from work.The lab gave a glowing report for the valk. stating  wear  metals were much lower than most engines let alone mtr/clutch/trans combo.One thing they made a note about was a silica level slightly higher than expected(dirt?)though not in the harmful range.
I'm sticking with mother honda's filters,this one is a keeper.
BW

[Hoser]

I bought a half dozen oem filters cheep at a swap meet, all new and in the box, about 9 years ago.  I have 2 of them left after 90,000 miles.  I like em.  Hoser