the lid is cut open on the top with an outewears filter covering the hole. i would say its pretty much the same as no lid or close to. there shouldnt be an air leak though. i did test for it. it all started when i realized the slides were in backwards and the jetting was way too rich to begin with. i had the stock needles in but it ran worse with them. just tried the others to see what happend. carbs cleaned several times, synced, and engine warmed up before lettin loose. tomarrow is planned for more work to figure it out.