I am looking to put a K&N filter on my 425 magnum and my wifes 325 trail boss. I am not really interested in gaining power, I just would rather pay a few more bucks for a filter that will last longer than a few rides. The question that I have is will I need to rejet the carbs after this change or will the increased airflow not affect the mixture enough to matter. I am not real excited about rejetting the carbs. What experience do any of you have with the K&N filters?

 

I installed a K&N on my Sport. I noticed a lot better and quicker throttle response. I then installed one on my 4 stroke Yamaha Kodiak. I didn't notice any better performance. Re-jetting wasn't necessary on either bike.

 

K&N's are fine in 4-strokes .
Use the factory *pre-filter* off of your factory filter. This will help keep crud off of the K&N and out of the motor .
A K&N flows much more air than a foam filter , it just doesn't filter as well in fine dust , 4 strokes get allong with them better than 2 -strokes .
If you leave your airbox in factory condition, jetting on your 4-strokes will be fine left in stock arrangement .
When ever you clean your airfilter , wipe a kleenex inside of your intake boot,between the airfilter and carburetor ,if it comes up black , you are eating dirt .

 

just installed one on my magnum last nite..i did notice a better acceleration.. as for the jets,i didnt have to change it.. i did notice that my fan had come on a couple of times,where i havent heard it on in a while but that was also while i was buried in mud over the tires waiting to be pulled out.. i dont think it was running too lean at all,just that i was running at idle and not moving..you shouldnt have to rejet..good luck