Jump to content
Sign in to follow this  

K&N air filter, worth the money?

Recommended Posts

I’m in the process of doing the FCR MX conversion on my ’06 “S”. I’ve done the 3X3 and a full exhaust system. Should I replace the stock air filter? I read the threads about the possibility of dirt passing through or around the K&N and I have to believe that if it is properly oiled and the sealing surface greased it should prevent this. How much better will the K&N breathe over the stock? Are all the Aftermarket foam filters the same? Are they better than stock?

Share this post


Link to post
Share on other sites

I have a K&N on my 05S and its never been an issue. I clean it after every ride so I am sure that helps. It is better than stock.

Many use other air filters like Twin Air and some other brands.

Do some searches or look at the parts link at the tops of the page I think there are a few in there.

Share this post


Link to post
Share on other sites

I have an 06 S and switched to K&N some time ago for my commute. Works great for the street.... then just switch back to the stocker on dirt.

Share this post


Link to post
Share on other sites

Use the K&N for both street and dirt and I have not had any problems with dirt on the intake boot as some others have on this site. Make sure you use enough oil on the filter as it is crucial for proper filtering.:applause: vanram

Share this post


Link to post
Share on other sites

Don't mean to hijack thread, but I just bought K&N filter for my S as well.

If switching from Stock to K&N do I need to rejet ? The K&N doesn't flow that much better does it ?

I have stock airbox & White Bro's E2 pipe. It runs great with stock filter now.

Share this post


Link to post
Share on other sites
Don't mean to hijack thread, but I just bought K&N filter for my S as well.

If switching from Stock to K&N do I need to rejet ? The K&N doesn't flow that much better does it ?

I have stock airbox & White Bro's E2 pipe. It runs great with stock filter now.

No need to rejet just because you changed the filter. The restrictive airbox opening is going to prevent you from any noticable improvement. Now, when you open up the airbox, you will have to rejet with a James Dean kit and then you will see a significant improvement, then wait til you get a FCR.

Share this post


Link to post
Share on other sites

One thing about the K&N is it's a bit heavier than the stock foam filter and it will slide around during riding. A great mod to solve this is the Proseal by PCracing.

http://www.pcracingusa.com/proseal.php

The Proseal keeps the filter tight to the airbox and creates a better seal without the mess of grease. It works great with any filter but works especially well on the K&N...

Share this post


Link to post
Share on other sites

ive had both, k&n and twin air.i would have to say the twin air beats the k&n hands down.i did a back to back test same rd same night and i got more speed with the twin air.

Share this post


Link to post
Share on other sites
ive had both, k&n and twin air.i would have to say the twin air beats the k&n hands down.i did a back to back test same rd same night and i got more speed with the twin air.
Of course you would, it will be slightly lean with a K&N compared to foam, just better mixture with the foan. Eddie says they are worth a little more power on a properly jetted bike, I think he said 1 hp.:applause: Make sure you use sealing grease on the K&N.:lol: vanram

Share this post


Link to post
Share on other sites

K&N filters will let dirt into your engine off road. This is the consensus of just about every dirt bike mechanic and rider in the know. K&N claims that they flow more air, this is true, but it is also true that they flow more dirt too.

Later,

Allan Greenblazer

Share this post


Link to post
Share on other sites
K&N filters will let dirt into your engine off road. This is the consensus of just about every dirt bike mechanic and rider in the know. K&N claims that they flow more air, this is true, but it is also true that they flow more dirt too.

Later,

Allan Greenblazer

I don't know about every dirt bike rider or mechanic in the know, I have never had the 'dirt in the engine' problem. I've done many offroad miles with zero problems. Many offroad racers use K&N exclusively as well as some dirt track racers with no dirt contamination of their engines, I have talked to them personally. Use sealing grease and oil thoroughly and you should have no problems.:applause: vanram

Share this post


Link to post
Share on other sites

Ditto on jetting for a K&N...it flows more air and leans out the mix if jets aren't changed. Same as the 3x3 mod leans it out...if you bore holes in your side cover you have to rejett...more airflow equals more fuel flow...

Share this post


Link to post
Share on other sites

Dirt in the engine isn't the kind of problem that shows up the next time you fire up the bike. It's the really fine powdery dirt that's the problem. When your motor gets tired and smokes like a chimney at 8k miles, that's the when you'll know that K&N isn't a dirt bike filter.

My opinion, if you ride anywhere remotely dirty (and can mean the street in desert areas like the South West) you need to run and regularly maintain an oiled foam filter.

Share this post


Link to post
Share on other sites
Of course you would, it will be slightly lean with a K&N compared to foam, just better mixture with the foan. Eddie says they are worth a little more power on a properly jetted bike, I think he said 1 hp.:applause: Make sure you use sealing grease on the K&N.:lol: vanram
i run k&n in all my vehicals so i'm not really putting it down but ever since i got one for the drz i had problems.could not get the bike jetted properly(this was with the stock carb though and i tried every main i could get.put the stocker back on a walla problems solved.)maybe i got a bad filter who knows.when i did the back to back test the bike was already jetted a little rich and i had the fcr and the pipe and cams.the bike at this time ran fine just i didn't get the same speed out of it but the difference was minimal.170km/k for the k&n and 174km/h with the twin air.i would of got the k&n up to the rev limiter but ran out of rd.

Share this post


Link to post
Share on other sites
i run k&n in all my vehicals so i'm not really putting it down but ever since i got one for the drz i had problems.could not get the bike jetted properly(this was with the stock carb though and i tried every main i could get.put the stocker back on a walla problems solved.)maybe i got a bad filter who knows.when i did the back to back test the bike was already jetted a little rich and i had the fcr and the pipe and cams.the bike at this time ran fine just i didn't get the same speed out of it but the difference was minimal.170km/k for the k&n and 174km/h with the twin air.i would of got the k&n up to the rev limiter but ran out of rd.
I don't really know what you are getting at, but in reading again what you are writing, it seems the jetting was more optimal for the foam than the K&N. You might have overoiled the K&N or it could have been damp from a cleaning?? In any case, it has been well documented that a K&N will flow more air than foam, and jetted properly, should make more power, about 1hp if I understand correctly. You cannot do back to back runs for a comparison with different filters without first rejetting. Oh, by the way, if you say that your bike is slower with a K&N then you are calling it down, unless you wanted to put a K&N on your bike to make it slower. :applause::lol: vanram

Share this post


Link to post
Share on other sites
Dirt in the engine isn't the kind of problem that shows up the next time you fire up the bike. It's the really fine powdery dirt that's the problem. When your motor gets tired and smokes like a chimney at 8k miles, that's the when you'll know that K&N isn't a dirt bike filter.

My opinion, if you ride anywhere remotely dirty (and can mean the street in desert areas like the South West) you need to run and regularly maintain an oiled foam filter.

MY first engine made it 28000kms wide open all the time before any problems, no wear or contamination, cylinder wall flaked off during my winter ride, could have been from the filter passing dirt, but not likely. Millenium has seen other cylinders do the same thing. Rest of engine was like new, changed valves as a precaution.:applause: vanram

Share this post


Link to post
Share on other sites
I don't really know what you are getting at, but in reading again what you are writing, it seems the jetting was more optimal for the foam than the K&N. You might have overoiled the K&N or it could have been damp from a cleaning?? In any case, it has been well documented that a K&N will flow more air than foam, and jetted properly, should make more power, about 1hp if I understand correctly. You cannot do back to back runs for a comparison with different filters without first rejetting. Oh, by the way, if you say that your bike is slower with a K&N then you are calling it down, unless you wanted to put a K&N on your bike to make it slower. :applause::lol: vanram
like i said the bike was jetted a little rich,the k&n should of worked better but didn't.the k&n filter was not over oiled(still what it came with from the box)and yes i did back to back runs and no i did not rejet(like i said the carb was a little rich already with the foam filter so i should of had better perfomance)and no i'm not putting them down like i said all the vehicals on the farm here have them only because you will get better fuel milage with them.i'm thinking i just got a bad one.and i didn't put it on the bike to make it slower it just came with the dj kit and pipe that i ordered.funny thing is that i like k&n and when i went to the another dealer and talked to there mech i was shocked to hear him say
get rid of it and put the stocker back on
his reasons were that he's seen many problems with them although most of these problems were sealing problems but never the less problems so as soon as i changed it back to the stocker problems all went away.but like i said i'm thinking i got a bad one.maybe if your close to the sunny okanogan this year you can have my k&n for free to see for youself:ride:

Share this post


Link to post
Share on other sites

heavily oiling the kn defeats all flow gains.

when they are run nearly dry is when they flow the best,but also risk dirt ingestion.it does happen.

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×