I have heard from someone that if you use a k&n filter that it will lean out the bike, so jetting would be needed?? This does not make complete sence to me, but I have always had FI bikes not carbed.

I have a oem exhaust, but just purchased the k&n filter, and would like to install it without harming the motor.

Next purchase is the jet kit, and slip on, but dont have the money at the moment...

should I install the k&n filter or not?

 

I have heard good and bad things with the K&N filters. My f4 came with one already installed with a stock pipe (although I have a new pipe on its way finally!) I have ridden for 3 years with the K&N and stock exhaust and the bike seems to be running great, but since I never had a regular filter I have nothing to compare it to.

I seriously doubt you would have to re-jet with a filter change.

 

rite on, you run the stock jets? Did you order a jet kit with that new pipe?

 

There are so many variables to that equation, no way to say for a fact that a certain part is going to make you have to rejet. Installing a K&N won't harm your motor. Due to production differences, you could have 2 bikes made right after each other and one need some fuel and the other not. You'll know if you need it, bike will be flat on topend. The tach will still climb but not as hard as it did before. Best way to tell if your new aftermarket part is worth the money is if bike runs like crap after you install it. Every hi-po part out there is designed to do one thing...get more air into your engine.
Best way to check if jetting is correct (in my opinion) is plug checks. The plugs will never lie.

 

Ya, its on the stock jets now and i did not even order a new jet kit for the exhaust...I am going to see how it runs first. FMF told me I may not need it, we shall see.

 

would be nice if you can get away without jetting

 

pretty much all carbed bikes are lean from the factory for emissions. By installing an air filter that increases amount of air getting into the cylinders you're leaning it even further, combined with a more free flowing exhaust you've improved the aspiration of the bike but didn't accommodate the changes with appropriate fuel delivery.