Was wondering if any one has any positive or negative experience? After reading a few threads and posts on it I was not that sure if it was worth it or not for the street.

K&N makes a few different filters that fit the Ninja 250. Most people that use a K&N filter, do so because it is better than the stock filter. They also do so when making small to large modifications to the intake/exhaust to obtain better performance. Whether it is a pod filter or drop in type filter, they both are used for everyday street or track use, it depends on the intake/exhaust set up.

If your bike runs fine and you are satisfied, leave the stock filter in, but replace it when it is time to. If you want a little better performance from you bike or plan to do any mods intake wise, consider a good alternative replacement air filter (https://www.ninjette.org/wiki/Air_filters_for_newgens).

Is it worth the cost? It depends on you. Most people would say a quality filter and a small performance boost is worth the cost.

On our bike and unless you are racing, it is a waste of money. If you still want something better than stock go with UNI filters or similar, 1/4 of the price and way better airflow.

Are we talking pods, or just replacing stock filter?

With pods... probably better to keep stock airbox but the pods make working on the bike super easy. My pods have gotten wet while bike was parked and I was in work 3 or so times and obviously affects air flow. Other than that, no problems.

If I still had stock air box, I would probably use a performance air filter, be it K&N or something else, why not?

I just put a new K&N filter in my bike, and I do not notice a crazy huge difference. Definitely has better airflow than the stock filter though, since the engine feels like it is more smooth and happier than before. My exhaust also changed its tone slightly, but other than that, I have not noticed a major performance increase. I got mine for a solid price, and it was time to replace the stock one anyway, so I figured why not go a step up and get the K&N. Cant go wrong.

It was for the stock filter I was looking at replacing in the future, I was worried over time as they say the increased air flow lets in more debris which is not good for the engine over time. I was wondering if there is any truth to that.

It was for the stock filter I was looking at replacing in the future, I was worried over time as they say the increased air flow lets in more debris which is not good for the engine over time. I was wondering if there is any truth to that.

There is some good info on filtration vs. restriction in this thread.
Review Update: Hurricane Racing Performance Air Filter (https://www.ninjette.org/forums/showpost.php?p=670375&postcount=4)

It was for the stock filter I was looking at replacing in the future, I was worried over time as they say the increased air flow lets in more debris which is not good for the engine over time. I was wondering if there is any truth to that.

you definitely do not want to let debris in there at all. nothing should get past the filter. when i removed my stock filter i had leaves, dirt, and grime in there. definitely want it to be as clean as possible to get maximum air flow for any filter

I just put a new K&N filter in my bike, and I do not notice a crazy huge difference. Definitely has better airflow than the stock filter though, since the engine feels like it is more smooth and happier than before. My exhaust also changed its tone slightly, but other than that, I have not noticed a major performance increase. I got mine for a solid price, and it was time to replace the stock one anyway, so I figured why not go a step up and get the K&N. Cant go wrong.

Exactly this ^

Both bikes have them. I like

I do have the Leo gp corsa slip on with everything else stock on the bike and with an upgrade to the air filter I was looking to make it a bit more efficient. Thanks for the info.

^ if you want fuel efficiency then you do not want I high flow air filter. More air means you need more fuel.
If you get a K&N they require cleaning and oiling to help them filter well

I would not expect to notice any gains on the butt dyno with filter change on this bike even with proper jetting. Someone said it best in another thread somewhere and I am paraphrasing but.

Even a high % increase of a little is still only a little :thumbup: