for Honda CB750 four K0-K2 with original Keihin carburetor
Keyster = KHV-03020
OEM = 16011-302-004
OEM = 16011-375-004
please check and adjust float valve level if you chang float valve.
level data you find by Keyster carburetor parts in this shop, search your model.
please clean your petrol system
change complete set, not only new valve in old holder.