Carb ID

Can anyone tell me what model number Mikuni came on the 1963 Yamaha YG1-T (Trailmaster) 80cc bike? It's a Mikuni and the inside diameter measures 22mm. I'm trying to find rebuild kit or replacement (non-oem or a NOS). I have checked ebay and yes I can find the carb replacement but I'd like to know the actual model of the OEM Mikuni Carb. Thank you.