Its usually between 2 and 4 mm below the bowl gasket.
Having them set well is important, but the most important thing is that they are as close to same height across all as possible.
GL.
Motorcycle Shop Owner/Operator
79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors