for GS750 Bj. 80-81 with original Mikuni carburetor
Keyster = KYV-29S20
OEM = 13370-11400
OEM = 13370-44080
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.