K&N Air Filter

I took the K and N out of the Rex and put a stocker back in. For $50 for a replacement filter v the stuffing around cleaning a K and N and Re oiling it I couldn't be pharked so I don't even buy the maintenance argument. I also kind of figure the guy in the Kawasaki factory who designed the engine probably knows more about air flow than I do

They go heaps better than standard with pods and an Ivan's jet kit. Just sayin'.

I took the K and N out of the Rex and put a stocker back in. For $50 for a replacement filter v the stuffing around cleaning a K and N and Re oiling it I couldn't be pharked so I don't even buy the maintenance argument. I also kind of figure the guy in the Kawasaki factory who designed the engine probably knows more about air flow than I do

They go heaps better than standard with pods and an Ivan's jet kit. Just sayin'.

Glenno you can't be serious mate ? Or the stock filter in a Rex must be a total prick to get access to ?

It takes about 2 minutes to wash the filters on the MFP12 after they have been given a spray with the K&N filter kit wash, blow-dry them, then a quick pump-spray with filter oil.

It takes longer to get all the other shit out of the way than the time I spend on maintenance anyway - and you have to spend the same time pulling everything out of the way to get to OEM filters anyway........

I have done the filters in the 12 3 times now, the cleaner kit is not even close to 1/2 empty and I reckon those filters (BMC) will still be on the bike in 10 years time ! NFI what a set of stock filters costs for a 12 these days but multiply it by 3 and that is how much I haven't spent on air-filters......

I took the K and N out of the Rex and put a stocker back in. For $50 for a replacement filter v the stuffing around cleaning a K and N and Re oiling it I couldn't be pharked so I don't even buy the maintenance argument. I also kind of figure the guy in the Kawasaki factory who designed the engine probably knows more about air flow than I do

unless it is in a very dirty environment I worked out with the 2 x filters for the 12R being replaced at the recommended 50k Kms it would take at least 100k kms to make it financially a better option when i got to 150k km. All the dyno tests done on the 12R with stock filters proved there was no gain in after-market filters at all, this does not apply for race filters but i would not use them on the road. I will add not all oem bike filters are equal

But hey, I bought some BMC filters anyway


I did a similar analysis with a Scott chain oiler, same result being not worth it financially.

When it comes to the crunch the oil added to the K@Ns is the killer for power.

I can change the filter in the Rex with a stocker in probably 5 mins and know for sure that it's getting air as clean as it should be without bullshitting around cleaning it and reoiling it. For $50 if that saves me half an hour then it's worth it. Just my opinion but for me I couldn't be stuffed.

I'm inherently a lazy prick too

Last edited by Glen on Thu Jul 12, 2012 8:32 pm, edited 3 times in total.

how much power does it kill ? Can a dyno even measure it ?

For the top 10 punters in ASBK - yep, it would matter to those blokes. No issue there.

but for the rest of us on road bikes - for a bike that makes 155-160hp in stock condition, if an oiled filter knocks off even 1hp (which I would highly doubt) - then seriously who would give a flying fuck about the loss of 1 or maybe 2hp ? That amount only represents maybe 0.5% of total power output ?

What really matters - is that over the course of the life of a replacement filter - if you do the filter every 12 months then after 3 years you are already ahead as far as servicing costs are concerned.

Depends what to value your time at.

K@Ns have a lot of oil in them from factory, i have seen a shootout with K@N's vs BMC race filters vs standed,the "race BMC " had 1hp on the standed filters ,the K@N lost 3 hp on the standed filters as from factory they had a lot of oil in them.I will try and find it again.

Yeah you only need a little film of oil..i used to use papertowel to clean the oil from new ones..

maybe the K&N's have a lot of oil from the factory - that actually doesn't surprise me much at all. 3hp loss does surprise me a bit though ?

As per Hoffy's post, I only use the lightest film of oil on the BMC's in my barge - using oiled filters hasn't changed the power delivery that I can tell ?

Glenno you lazy prick - heh those old Rex shocks of yours look 100% excellent on the Z1000 mate - they have a nice gloss to the black which matches the new powdercoating really well....

As per my post last page that filthy filter is 30,000km's old and it only sapped 1hp which is a acceptable variable on a dyno which you could say it didn't affect power output.

It's really hard to get information of before and afters on dyno's for air filters.

Here is a site of stock vs aftermarket but its magically dissapeared http://www.australianauto.com.au/HTML/I ... %20Out.pdf

I picked up my stock air filter for 38 bucks from the USA so that gets me 3 filters to 1 K&N (if I pay full price)

On saying all this I run a K&N in the misses car cause I scored it cheap and got the re-oil kit off a mate for free

Read this !
http://www.google.com.au/url?sa=t&rct=j ... qEgRWVMt6Q

Read this !
http://www.google.com.au/url?sa=t&rct=j ... qEgRWVMt6Q

I read that 3 years ago

its not about K&N's being *better* or *worse* than EMC's - the fact is they are both oiled air-filters. Sometimes the yanks get all caught up in pissing contests based on a 10th of a second here or there - its just a pissing contest.

The benefit is in longevity from being able to clean and re-use them. Like one of the posters says in that thread - a 1hp variation in a dyno reading is an acceptable variable between runs. It could be something as simple as reduced traction in 1 run over another - the end result though, is that for everyday real-world riding, most riders would not know or feel the difference wether they had a clean OEM filter, a dirty one, a K&N or a BMC. The difference in response is going to be infinitesimal (jeez thats a hard word to type after 4 jimmies ).

What is *not* infinitesimal - is the difference in replacement costs vs maintenance costs.

Glenno you lazy prick -:

You got that right....tightarse

I use a Pipercross race filter on the 10, and found them very very good, had used them prior as well, but this was the 1st race filter.
On the box they claimed in their speil about HP gains, with the filter i bought, they say 4.5/ 5.5 HP gains, it was going on the dyno to get the map clearned up, so a run was done to get a graff, then filter fitted and back on dyno, map redone... gain 1.5 HP... thats with PC3 and pipe with cat bypass.... so did i notice any diff.. of course not. be are so easy to clean and put back, well worth it i think.

But on that note, we got 1HP extra with the cat bypass fitted, and tristan got 5 HP net gane by somethings he uses to do when he was building race engines for staford. so all up for very little expence u can gain say 7/8 HP, which is a good gain i think and with a TRE fitted u get a sharper throttle from closed ect, so that gives u a good sharp engine for bugger all, so thats got to be good