Had a little problem with mine.
bike had a flooding problem a while back leaking back throgh the air box leaving the new K&N filter soaked in petrol. So I washed and re-oiled using genuine K&N products, then left it in a zip lock bag for a few weeks. went to put it back in and found it had shrunk. probaly about 5mm, enough so it wouldnt fit over its locating bits in the top and bottom halves of the airbox. Had to warm it up with a hot air gun to soften and stretch to fit again.
Maybe the rubber reacted with petrol?
Probly best if it happens to anyone else is to clean and re-fit ASAP.
Mine was left out for an extended period due to waiting for me to pull finger out and get carbys off to fix the flooding prob......its still waiting, put the filter back in cos wasps are active building nests and didnt want my open airbox as prime wasp real estate.
