Motorbike air filters

wazza300 · 20 Dec 2015 at 18:37

Are K&n and the like aftermarket filters actually any good over stock? just wondered if its worth the spend and any realworld bhp gain at all?

^JP^ · 20 Dec 2015 at 19:05

I think it is only worth it if the engine is then mapped for the new filter.

When I got the Termi cans for the 899 they came with a new air filter and up-map.

The filter is a Sprint Filter P08 and I asked if it was really needed as installation is a pain but it is as the map is designed around it giving a more consistent airflow than the stock oiled cotton filter.

My bike is meant to be 155hp up from 148hp but I never tested it, compared to a stock bike mine does feel smoother through the midrange but I think that is down to the full combination of parts.

Craig321 · 20 Dec 2015 at 19:45

As above, I've only ever heard of it making a difference if you map for the filter and even then it can be unnoticeable. I wanted to do it on my Speed, but it's running so nicely at the moment that I'll leave it for the time being.

BigRazer93 · 20 Dec 2015 at 21:04

I've got an k&n air filter on my sv and seems fine. IMO it likes to be reeved when up in the revs, it seems to pick up better than over a standard filter.

My bike hasn't been remapped or anything. All I had to do was alter the idle speed when I installed it and that's it. Sounds good too when on the throttle.

wazza300 · 20 Dec 2015 at 21:29

Yeah that's what I was wondering,whether it added bhp without any other mod like a power commander or unrestricted pipe ect

Freeman · 20 Dec 2015 at 21:38

There's an air intake and filter mod you can do on the Bonneville. No bhp increase but does improve the smoothness of the throttle apparently.

Sounds like too much effort for such a tiny gain.

(needs all sorts of ECU changes to stop warning lights from staying on)

BigRazer93 · 20 Dec 2015 at 23:08

Personally, I think it depends on the bike, for example. The k3 650 out of the factory is ment to be running richer than normal, so adding the filter and having an aftermarket can would lean things out a bit, making it a good ratio. However, this doesn't mean every bike will.

K&N say you don't need to alter fuelling or anything what so ever, won't kill the engine etc, and if they say you don't have to that's good enough for me, as if they lied about it surly it wouldn't be legal?

I like the k&n products. You can wash and re oil the filter not throw away. Oil filters come with basically a nut on the end of the filter so you don't have to faff about with adopters to get them off.

TripleT · 21 Dec 2015 at 08:30

Ben-Irvine93 said:
Personally, I think it depends on the bike, for example. The k3 650 out of the factory is ment to be running richer than normal, so adding the filter and having an aftermarket can would lean things out a bit, making it a good ratio. However, this doesn't mean every bike will.

K&N say you don't need to alter fuelling or anything what so ever, won't kill the engine etc, and if they say you don't have to that's good enough for me, as if they lied about it surly it wouldn't be legal?

I like the k&n products. You can wash and re oil the filter not throw away. Oil filters come with basically a nut on the end of the filter so you don't have to faff about with adopters to get them off.

They would say that, as otherwise none-one would buy them as they couldn't be bothered with the cost and hassle of remapping!

tom_e · 21 Dec 2015 at 08:41

Ben-Irvine93 said:
I like the k&n products. You can wash and re oil the filter not throw away. Oil filters come with basically a nut on the end of the filter so you don't have to faff about with adopters to get them off.

So do the HiFlo racing ones which come in at half the price of the K&N ones as well in that case you're almost certainly just paying for a name. Saying that they should only really be hand tight anyway.

I did some reading on normal and reusable filters when I was picking up all my bits and the general consensus was they don't make a great deal of difference and can end up causing fuelling and flat spot issues iirc so I just stuck to the standard.

Craig321 · 21 Dec 2015 at 10:56

I read somewhere the K&N ones, rather than allowing more air, just keep cleaner/clear for longer and are also maintainable/lifelong (million mile warranty).

tom_e · 21 Dec 2015 at 11:03

Craig321 said:
I read somewhere the K&N ones, rather than allowing more air, just keep cleaner/clear for longer and are also maintainable/lifelong (million mile warranty).

The only way to stay cleaner for longer is by being a more inefficient filter in terms of catching particles and allowing more air/crap through though which doesn't sound great, also the oil residue can mess with any sensors if they're installed.

Craig321 · 21 Dec 2015 at 11:05

tom_e said:
The only way to stay cleaner for longer is by being a more inefficient filter in terms of catching particles and allowing more air/crap through though which doesn't sound great, also the oil residue can mess with any sensors if they're installed.

Yup, I have also heard that about K&N filters, that people have had dirt on the wrong side of them. I was looking at it last night... doesn't seem like a worthwhile upgrade.

A lot recommend the BMC filters as an alternative.

Tefal · 21 Dec 2015 at 11:19

tom_e said:
The only way to stay cleaner for longer is by being a more inefficient filter in terms of catching particles and allowing more air/crap through though which doesn't sound great, also the oil residue can mess with any sensors if they're installed.

Or you know increasing surface area....

By using bigger corrugations and more material you can catch the same amount of cap but provide more unclogged area for air to pass through.

Not saying k&n or any make is better than another but saying that the only way to stay useful for longer is by being more inefficient in terms of catching particles is false

wazza300 · 21 Dec 2015 at 11:19

They supposed to increase airflow yet still filter out the crap as good if not better than an OEM filter,I have a dna one fitted in my zx10r but it came with the bike,im still not sure whether it's worth spending on one if your not planning on going down the full exhaust and remapping route

Tefal · 21 Dec 2015 at 11:31

Main reason I see for buying something like the k&n filters is so you can clean and refit it cheaply and so much more ereguarly than you could a disposable filter having to buy one each time

wazza300 · 21 Dec 2015 at 11:37

You can wash the stock OEM sponge ones,I washed mine about 5 times in a bath of petrol and re oiled it,it eventually broke down so I replaced it

tom_e · 21 Dec 2015 at 11:38

Tefal said:
Or you know increasing surface area....

By using bigger corrugations and more material you can catch the same amount of cap but provide more unclogged area for air to pass through.

Not saying k&n or any make is better than another but saying that the only way to stay useful for longer is by being more inefficient in terms of catching particles is false

This is a fair point that I hadn't even considered

My brain is already on holiday for Christmas, that's my excuse.

Dogbreath · 21 Dec 2015 at 12:14

tom_e said:
The only way to stay cleaner for longer is by being a more inefficient filter in terms of catching particles and allowing more air/crap through though which doesn't sound great, also the oil residue can mess with any sensors if they're installed.

The object is not for an airfilter to stay clean, but for the airflow to not significantly degrade even when it has captured a lot of dust/dirt.

Tefal · 21 Dec 2015 at 13:58

wazza300 said:
You can wash the stock OEM sponge ones,I washed mine about 5 times in a bath of petrol and re oiled it,it eventually broke down so I replaced it

all my hondas have been disposable paper filters.

benji182 · 21 Dec 2015 at 18:06

If this is for your ZX-6R this is from the K&N website Wazza.

http://www.knfilters.co.uk/news/news.aspx?id=2459

K&N Increases Performance And Horsepower of 2009-2012 Kawasaki ZX-6R Ninja Sportbike Motorcycles

K&N racing air filters are designed to have just two layers of cotton to provide even less air restriction than the standard K&N replacement street air filters. Fuel management modifications will be necessary with this racing filter, unlike the standard replacement air filters. K&N racing air filters come with a one year limited warranty and are washable, re-usable and are easy to fit.