Hi,is it a pattern or genuine filter? I look after about 20 of these for a customer and have not found a pattern filter to fit yet,I only use genuine air filters,oil and fuel pattern filters never been a problem,just the length of pattern air filters. If you force them in they will either strip the thread or split the lower air box fixings when tightened,if stripped you can slightly enlarge the holes if top casing and fit next size up screws.Even the genuine filter looks a little long,but ends are softer and squash when tightened to form good seal,hope this helps,john.