Hi there! K&N vows that no rejetting is needed when installing one of their air filters if no modification has been done to the engine. That's my case, all is stock except for the Arrow exhaust.
Since I put the K&N my bike runs very lean, reluctant to increase rpm and even vibrating more. Installation for this model is a little tricky because the filter isn't exactly as the original (quote:"the baffle of the filtercharger must be slipped between the two poles and the original position, just resulting a little backwards"). For me this is a little confusing and not sure if I put it on correctly.
Have you had a similar problem? I'll appreciate your advice. Thank you in advance.

Emilio

 

How are you determining a "lean" condition? Best way I know is to check the plugs for correct color. Sandy brown is good, black is rich and whitish is lean. Other ways include an engine getting hot or overheating quick when lean and black silt and smell of unburnt fuel during idle while too rich.

Anyhow, provided it is actually lean and not rich running, you should check that everything is sealed good and that air is not by-passing the filter. What I've seen before is too much oil use on these re-usable filters causing a rich run. Too much oil use likely caused by the interpretation of what the filter manufacturer instructs as oiling "liberally". Rather than "liberal" I would say thorough coating resulting in no dripping of the oil. Also, let the oil be drawn into the filter before replacing in bike.

Another thing to keep in mind is while just changing 1 component may not be enough to throw the system off balance, adding into the mix other changes compounds the overall effects which may eventually result in a system that is off balance. Therefore, keep in mind all changes while adding more changes. Capeesh?

Cheers!

 

Hi Emilio. I don't particularly know about the vibration or the instalation of the K&N, but I have read reports that they actually reduce the power output on CBR's. I think a menber from this forum did a dyno test.
Check the clamps that go from the airbox to the carbs, they are kind of a pain in the butt to seat correctly and could be letting in even more air.
Thats all i got for you man, good luck

Danny

 

dyno stage one jet kit comes with two diff, needles , use the 110"s and it'll sing.....

 

Hello!! I found the problem! The thing is when I mounted the K&N I didn't put any seal to close the airbox. Maybe the two seals (they are two according to the parts drawings) went to the trash bin attached to the old filter without my noticing.
Then I put two home-made seals on top and under the airfilter and sealed the airbox. Now the Fireblade pulls hard again . Since the old filter was stuck with dirt I guess I'm going to get a better mileage.
Many thanks for your helpful advice and ride safe.

Emilio

 

There you go. Nice work. I believe my suggestion above was spot on yes? And I quote myself: "check that everything is sealed good and that air is not by-passing the filter". ;-)

 

Hey Adam !! You were spot on! But don't relax too much... Since I tamper with the bike now and then I'm very able to mount whatever thing incorrectly again. Thanks again and Cheers!

 

K&N's don't flow as well as stock paper filters, Sure you can wash them so they're reusable and will last you forever, but they don't flow as well as a clean stock paper filter. You're better off to just replace the paper ones when they get dirty than to clean the K&N over and over cause it will never be as good as fresh paper.

 

wonder if this was my issue as well, i installed the k&n and the thing ran like trash. then again i have full system and no clue of stage jetting is in the bike. what are these clips you are talking about?

 

Changing air filter shouldn't cause significant differences in air flow. However, removing it entirely will. Or stopping things up with a bad filter will too.

Changing your exhaust is a major enough change to the engine that you may need to adjust the idle. If things can't be set right with idle adjustment, then rejetting is required. In the case of FI, remapping.

Exhaust creates back pressure, which effects the airflow. Increase pressure will increase richness, and decreasing will lean things out. This is the theory.

I say dump NOS into 'er and she'll sing. Yeeehaa!!!

Hope you have good grips, gloves and a strong hold on 'er too.

Cheers!