K&N high flow airfilter

[OGjackafidy]

I installed one on my bike this morning and was just wondering what the horsepower gain is if there even is any

[Skippii]

Correctly jetted, you gain about 2, maybe 3 hp

If you don't rejet, you'll probably lose power and your bike will run worse.

Edit: I was thinking more about the K&N Pod filters, I don't have experience with the regular filter. So, you might just gain 1 hp with rejetting, if you don't rejet, it might run only slightly worse.

Edit #2: If you have a 2009, why are you asking in the 1986-2007 forum? What bike did you do this on?

[JCCJMM_]

I would say about zero gain. There are alot of variables with regards to airflow.

[OGjackafidy]

Whoops my bad I thought this was on the new gen. I guess il rejet when I get paid. Is a high flow make it run to rich?

[CynicalC]

Search. Seriously. While you're at it, look up what rich and lean mean and use logic to figure out which one your bike is now.

[Alex]

/moved to new-gen area

[Skippii]

Originally Posted by OGjackafidy

Whoops my bad I thought this was on the new gen. I guess il rejet when I get paid. Is a high flow make it run to rich?

Rich means too much gasoline, not enough air.

Since you've increased airflow, you're going to be running lean.

[Boom King]

Well you said you installed it, so do you "feel" like you gained any horsepower?

I can provide input from my own experience. K&N will claim x% performance gain but in reality, any difference is barely noticeable. I installed one in my bike, not because I believed the marketing hype but only because I needed to change the air filter and the K&N was easier to acquire than the OEM one. Based on my riding experience before and after the change, there was no difference. Since the perceived performance gain is nil, I would actually recommend people to keep using the OEM one especially if they ride on dirt or unpaved roads often. Just by looking at them, you can tell that the foam OEM filter does a better job of screening out unwanted particles than the cotton gauze type of the K&N.

[blink]

Originally Posted by OGjackafidy

Whoops my bad I thought this was on the new gen. I guess il rejet when I get paid. Is a high flow make it run to rich?

Running rich sounds sickk...

[rusninja]

are we talking about one you put in airbox or a cone filter?

[ninja250]

You should notice an increase, properly jetted.
Box filter or pods..

You notice it on FI bike, dont' see why not on carbs.

[ninja250]

Originally Posted by Skippii

you're going to be running lean.

And since his bike is already lean from factory, it will only run worse with K&N and not jetting... likely.

Don't forget to shim.
Makes huge difference. Richen out the mid range a ton. Lots easier to ride. Much more friendly and responsive bike.

Jets fix top end WOT. If it don't get up all the way in sixth it probably needs jetting.

[Boom King]

Originally Posted by ninja250

And since his bike is already lean from factory, it will only run worse with K&N and not jetting... likely.

In theory, one would think that but in practice there was no noticeable difference gain or loss. At least this was my experience and my bike is not jetted. If something like a little K&N air box filter made that much of a noted difference I'm sure the community would know about it. The other thing to consider of course is not all bikes are tuned equally from the factory so individual results may slightly vary along a narrow margin.

[ninja250]

I put one in the old Alstare FI.
Felt a difference.

I can't be positive the difference wasn't just from the K&N filter or having a new filter all together but I'm pretty sure some slight difference was felt.

It's not like it's a wopping thing though.

The jetting/needles/shims is what is really going to tune your monster.
Pods open her up quite a bit also. Get those nasty boxes out of there.

I currently run pods and stock exh.

[Skippii]

Just because your bike doesn't run noticeable worse doesn't mean it's not running worse.

This is not to say that you NEED to rejet your bike. You might notice differences with drastic changes in altitude that you might not notice otherwise, or you might not.

My issue here is that K&N filters are expensive. They're expensive because they're performance products designed to increase horsepower. Why pay more for horsepower if you're going to use it in a way that reduces horsepower? You might as well just use a dirty filter and get the same power loss.

[Boom King]

Originally Posted by Skippii

Just because your bike doesn't run noticeable worse doesn't mean it's not running worse.

Fair enough, it might be all perception. Just like how some people say that their bikes run better on 91 grade gasoline. On the other hand, sometimes no noticeable effect does mean that there's no effect to be noticed. Until something conclusive is presented, all possibilities are on the table: gain, loss, or no impact. Point is that any supposed performance impact is so minute that people should not be losing any sleep over something so immaterial.

[5evenz]

I have a yoshi slip on and K&N air filter. the guy put them in before i got my hands on the bike. ran great but after removing snorkel it ran like ****. super lean with Weird idle, crappy throttle response and felt like it took longer to warm up. put it back in and used an OEM filter and its waaaay better. gotta shim still but I would say get a K&N if you want a cool pink squishy filter instead of boring stock. Meh...