RE: Welcome to Club SAITO !
The FG20's operating characteristics are somewhat different from a FA125 though many parts will interchange.
My experience is that the original Saito ignition with the big inductive timing pickup is nothing but trouble. I changed mine out to the RCEXL ignition.
In spite of the carb having a built in pump, it is very weak and the fuel tank needs to be as close to the carb as possible.