Is there a prime on the original Savage vacuum petcock? If you have a prime set it to prime and try starting while on prime with choke on. If you smell gas, you've flooded it.

Mine does not like the choke, may start with choke after a long time sitting but it wont run with choke on for long. During the riding season I never use the choke to start it.

But after the bowl is full, would you put the petcock back on ON or leave it on PRIME to start the bike?

Yes, you can leave it on prime to start it. No harm w/ leaving it on prime forever, but then it would be the same as any bike that has an "on", "off" and "reserve", and if the float valve ever sticks, it could drain gas into the crankcase oil, or all over the floor. The vacuum operated petcock is a saftey valve,.....in that the only time gas will gravity flow from the tank is while the engine is being cranked or running, so therefore it elliminates the need to manually shut the gas off when stopping the motor. I like the feature, but some consider it a problem waiting to happen, and opt to change out the valve to a manual controlled valve.
But whenever you suspect a lack of fuel problem, turn it to PRIME !

Whats the difference between prime and on?