Sport Air Filter for 1½" SU carburettor  Ref: CXE031

The venturi opening is 1.37" (34.8mm) not 1½" (38mm) and matches or exceeds the choke size of the (nominal) 1½" SU carburettor. The additional 13.5mm Ø hole shown at the 8 o'clock position is for the oil breather pipe and should be taped off with oil resistant tape or a small bolt and two washers. Although the bolt is not captive, the chrome domed nuts can be tightened sufficiently without the need to hold the heads.