Carburetor Bell Mouth for Vintage Motorcycles. The ID is31.28 mm. Height is 94.77 mm and OD at air intake opening is 53.90 mm. Came in a tub of other sizes and types from purchase of European Motorcycle Inventory. Consult your local motorcycle shop expert for confirmation of your application. This one mounts with the use of 3 pins at the base of the bell mouth and where it would mate to the carburetor.