Your mileage may vary, but mine ran like poo without the filter, just trying it out. The little inlet hole seems to drown it at idle, if there is no restriction at all (filter). I have had good luck with the "skull head" and the coffee strainer type filter box. I like the coffee strainer one better, keeps more dust out, and the screw to release the cover is on the side. The plate stays on the carb.
Originally Posted by anim8r
took the air filter off my china girl for a test run today, just to see how it works with more airflow. DANG what a difference! I couldn't believe the improvement at takeoff. I liked my red skull, but it looks like I'll be replacing it with a microphone screen or a mini strainer or something.