My K&N filter fits into the airbox but the top won't fit on it because of that curved piece of plastic on the top of it. I was thinking of cutting a bit off the top and bottom of the filter mouth (the flat parts on the top and bottom) because that would lower it, centering it infront of the hole in the airbox better, and allowing the lid to fit on. Maybe I will file down the curve on the lid that hits it too? Anybody else have this problem...how did you go about modifying it???

 

I wouldn't cut it!! Does your filter have a tab on the top and bottom? The tabs should fit in the bottom of the air box and top into the lid. I think one of them is wider than the other make sure you have it in there right. Mine fit just fine when I was using the K&N Filter. Make sure the lid is seated properly on the top tab of the filter. This is a very crappy design by Yamaha because you can't tell whether the filter is secured after you put the lid on. Be Very Careful you get it put back together or you will be doing a rebuild before you know it.

 

i know this isn't what you want to hear, but the best thing you could do is get rid of the stock air filter set up completely. The Pro Design system (or similar) offers positive, clamp on style filtration. It also allows the use of foam or K/N, which ever you prefer. No more worries about whether your filter is seated correctly or not. It could save your motor's life someday.

 

The problem is the thing on the lid of the airbox. If you look at it it curves to hold the stock filter down. On the stock filter the plastic is flat but the part where the foam is on the K&N is rounded, unlike the K&N where the foam matches the profile of the plastic.