For further assistance, you may want to consult:

When he finally hit the electric start, the bike didn't just cough; it roared. The BS25 was breathing again, its patched soul turning ancient vacuum into forward motion. specific jetting specs for a stock setup, or are you troubleshooting a tuning issue like a hanging idle?

A "Mikuni BS25 carburetor diagram patched" is the digital equivalent of a band-aid on a bullet wound. Use the diagram to understand the original airflow and fuel curves, then use that knowledge to buy replacement parts.