Am wondering if any one knows if you remove the HAC system do you remove the plug that is located in the air inlet that goes to the needle jet passage. This is normally open on most Mikunies. Also, How about the opening that the tube is on that goes to the Hac unit (not the float bowl vent line, but the one that is on top. Thanks Kootenay for the prev responce. This unit is on a 2001 500F. Am going to jet it same as MXZ 500F and have specs for that engine.