Needle valve for the Mikuni BDST series carburetors as used on, amongst others, the Yamaha FZR1000 Exup.
Viton-tipped for superior sealing qualities.
Mikuni part number: 3GM-14107-17-00
Although these carburetors were originally delivered on the above mentioned models of motorcycles, they are often transplanted onto other bikes and engines so the range that these diaphragms might fit is much broader.
Alternatively, your bike might have been equipped with different carburettors during its life so please verify that the diaphragm shown will fit your bike.