Old mower gets a new carburetor (UPDATE)

March 28, 2021 (scroll down for an update on April 7, 2021)

Yesterday I posted that I had put a new carburetor on an old Poulan Pro mower that's been sitting in my shed and has not run for at least a year. I mentioned that I ran out of time to test it then, but I have now done so. I am happy to report that it started on the second pull! The engine runs smooth, but it does smoke:
I wonder if it is because it has sat so long and had leaked some oil that needs to burn off. It could very well be a worn cylinder or maybe even an obstruction in the air breather tube. More investigation to come.

UPDATE April 7, 2021
I changed out the SAE 30 oil that was in it for 5W30 (recommended by Briggs & Stratton) and, voila! No more smoking.
I sharpened the blade and mowed a little with it. Runs great!