k&n 0990, major improvement ?

[tac12345]

i currently have the k&n filter that fit the stock airbox.

I was wondering if the 0990 filter is a major improvement at high speed ?

[greg737]

k&n 0990, major improvement ?

Just by itself? Not really, not much.

A free-breathing air filter is just one piece (and a small piece at that) of what has to be a "whole system" approach to gaining more power (which equals more speed, and therefore more top end). And I'm speaking specifically to your situation, working with the EX-250, because the smaller the engine the smaller the margin of effect you'll get from any single change to it's configuration.

In other words if you add a K&N filter to a big V8 engine you'll get an improvement in horsepower that sounds nice when you say it, "10 horsepower or 15 horsepower" but taken as a ratio of the engine's total output it's not much at all. Now imagine the same ratio applied to the tiny bit of horsepower produced by your EX-250.

If you want real, noticable change as a minimum you should do the filter, re-jet the carbs and add a full system 2-into-1 exhaust like the Area P.

Want to go further? Jettison some vehicle weight (i.e. the lighter 2-into-1 exhaust helps, trash the center stand, go on a diet). Further? The Fuel Injection kit that's being talked about here on the forum will optimize your air/fuel ratio at every throttle position and engine speed. Short of a turbo, that's as good as you can get.

More top end? Fold the mirrors back and tuck real tight.

[tac12345]

Originally Posted by greg737

If you want real, noticable change as a minimum you should do the filter, re-jet the carbs and add a full system 2-into-1 exhaust like the Area P.

I've done that already the 0990 was the last step before spending big $$$$

[greg737]

Well in that case I'd say yes, do the 0990 swap. The 0990 will complement the free-breathing exhaust setup most at high RPM, so that will help you out at the top end speed which seems to be your major concern here.

If I could offer a suggestion on the stock-airbox-out, K&N 0990-filter-in process. When you take the airbox out, don't damage it. Instead, when you get it out you should modify it by cutting off the section forward of the battery holder and also retain the floor of the airbox forward from the battery holder section.

This allows you to reinstall the modified airbox as, primarily, a battery holder, but also it gives you the floor of the old airbox as a platform on which to mount things as you do further modifications to the bike because there's a good bit of space between the batttery holder portion and the back end of the K&N 0990 filter.

I did this with my airbox when I did my fuel injection conversion project. The airbox is really high-quality plasitc (very strong, rigid, fuel-proof, with strong attachment points to the bike's frame). Now I have mounted my FI fuel pump, my fuel pressure regulator, the controller for my wideband O2 sensor and a bunch of wiring on the the old airbox floor in the area behind the back end of my K&N 0990 air filter.

[tac12345]

ultimate top speed isn't my goal, but to have a better acceleration between 130-145 kmh

Also, thanks for the tip about the cutting

[greg737]

I was wondering if the 0990 filter is a major improvement at high speed ?

I guess I misinterpreted this statement.

[gt_turbo]

i'm not sure if that cutting method applies for the newer gen 250's. just follow the DIY air box removal on this site. do a search. some people resort to cutting the air box in half with a sawzall. it is possible to take it out relatively unscathed, but it takes patience and finesse.

[almost40]

Its just another peice of the "modding"