K&N type filters

alanw · Post by **alanw** » Sun Jun 15, 2008 6:29 pm

It seems keeping the air box is preferred, but I really don't want to. So what are the reasons for keeping it , visa verse against a k&n type. Or can anyone point me to an article to explain. Alan.

Cliff · Post by **Cliff** » Sun Jun 15, 2008 6:35 pm

There are many issues with removing the airbox.
Sure someone of more knowledge will post soon, i understand why but it's a right mouthful to put into text.

alanw · Post by **alanw** » Sun Jun 15, 2008 6:55 pm

Cliff, I though that, so I mentioned any article I could read. As long as it doesn't do engine damage.... I can like Rossi ride around problems

Alan.

Cliff · Post by **Cliff** » Sun Jun 15, 2008 7:03 pm

I believe by removing the airbox you will lose the surge tank effect, thus creating flat spots in the lower/mid range. It's all to do with air pulses, and the air resevoir available in the box. All the racers retain the air box, even if modified, they still keep it.
Phew! That was hard after a bottle of Merlot

.

the-elf · Post by **the-elf** » Sun Jun 15, 2008 9:41 pm

As above, in fact a bigger air is what is needed. Also fitting pod type filters will effect the jetting big time, If you do it then have a couple of hours on a dyno to get the jetting right.

mgtkr1 · Post by **mgtkr1** » Mon Jun 16, 2008 5:47 pm

at the very least go up 4-5 sizes up for safety. even then it may be lean? tbh i dont like pod filters. they do give gains to a degree but your losing a lot more in the midrange. the best way without making/fitting a large airbox is the stocker with the lid/half the lid removed. at least it was in the early 90's!! mj has a good easy solution thats worth a bit of a free gain. put small ally spacers under the front of the a/box lifting it 25mm. this gets more air in the airbox but you need to seal the engine area off for best/any gain. the sound is ace btw. i have semi open carbs with a heatsheild/HRC type shroud that works like a very un closed airbox if you get my drift? eventually i will have ram air like elf and co,. tbh the std airbox is very good if a bit small but it does the job and isnt as restrictive as people think. with basic mods it can work well. remember to jet up though. as elf said, dyno time is a good idea.

SHimmer45 · Post by **SHimmer45** » Mon Jun 16, 2008 5:51 pm

my last KR1-S had pods on and did howl like a good un.
be interesting to see if the airbox sounds just as good

alanw · Post by **alanw** » Mon Jun 16, 2008 6:27 pm

STD airbox then

. Alan.

mr_bungholeo · Post by **mr_bungholeo** » Mon Jun 16, 2008 7:33 pm

every bike ive ever owned that had k n n filters ran crap...there is a reason standard bikes have airboxes(it costs more to produce)its cos it works.....

falconman · Post by **falconman** » Mon Jun 16, 2008 10:30 pm

My experience - 35mm carbs with pods = 125mph, 28's with stock airbox = 133mph.

Matty21 · Post by **Matty21** » Tue Jun 17, 2008 9:51 am

with the pods isnt it basically , as an example putting your head out a car window at like 110mph and trying to breath?

with the pods it struggles.

Leewc · Post by **Leewc** » Tue Jun 17, 2008 9:52 am

Remember one of the reasons for an airbox is that it keeps the air cool. With K&N type filters your carbs would be sucking in warm air from the airflow around the engine.

I'm sure people realise cold air = more power.

RAVEN · Post by **RAVEN** » Tue Jun 17, 2008 12:46 pm

"POD" filters are only good for top end of the rev range stuff eg : racing they work best when your ringing its neck all the time .

Standard air box and a good quality filter is the way to go , they are designed to work well at all points in the rev range and flow/restrict the air for the best engine peformance.

alanw · Post by **alanw** » Tue Jun 17, 2008 8:46 pm

OK I have an R6 shock fitted so the volume of the air box will be reduced !
So plan B !, make a new air box. Apparently a bigger air box than std is an advantage ????. OK so I extend it to occupy the space where the battery sits.... But is shape important ?? or just shear volume. then I would look to re-site A ! battery something on the lines of what ELF's done. I would junk the R6 shock but my swing arm is based around it

Again thanks for the help I was going down the wrong path. Then again I know my way well down the wrong path. been there lots.....Alan.

the-elf · Post by **the-elf** » Tue Jun 17, 2008 9:52 pm

If you do a search I have posted some pics of an extended airbox that I am working on. Basically the carbs sit inside the box in GP style, which also means they run at air ram pressure instead of having to feed the carb overflows into the airbox. This is only needed for a air ram set up.

Swapping the big heavy battery for one of the lightweight jobbies I use isn't a problem on a race bike if your doing the same on a road bike (my old KDX had the same set up) then the battery (which the KDX didn't have as standard) will only run the eletrics for about 5 mins without the engine running. You could always buy two and wire them in pararell.

If I was doing it, which I am (but very slowly)

I would fit an air ram an extend the air box both forward to enclose the carbs and backwards to where the battery was and fit a light weight rechargeable battery. Shape does have an effect, but its alot less than the volume and as standard the air box is on the small size. My problem is that I am crap at doing glass fibre work. I also need to figure out a method of getting the fuel lines into the airbox, but allow the tank to be easily removed.