I had this happen as well. Some of the K&N filters have the wrong size opening. K&N replaced mine for free. I wrote them a detailed letter including measurements. Here is the part that gives you the dimensions
The new K&N is in (on left) and the hose fits it like a glove (I switched hoses and both hoses are identical in measure). The new filter is 2 mm larger everywhere (opening OD/ID and both end diameters of the filter) Opening has 85 mm OD compare to the original (on right) having a 83 mm OD. (New filter (left)has 75 mm ID at opening versus 73 mm on the original)
The new K&N is in (on left) and the hose fits it like a glove (I switched hoses and both hoses are identical in measure). The new filter is 2 mm larger everywhere (opening OD/ID and both end diameters of the filter) Opening has 85 mm OD compare to the original (on right) having a 83 mm OD. (New filter (left)has 75 mm ID at opening versus 73 mm on the original)