[Bobcat]

I run a locknut ( nylon ) down the threaded rod and put a flat washer on top of it . This gives the air cleaner top/lid something to bottom out on when you tighten the lid down . On some of the thinner lids , they flex and can cause the wing nut to come loose . You can also put a rubber washer between the lid and a flat washer and then the hold down nut .... helps absorb some of the vibration .
I also use a lock nut ( jam nut ) on the threaded rod that screws into the carb itself .

Bob