Year and model

[Jim Becker]

Your symptom is a common behavior from a bad condenser. Out-of-box failure of new ones is not uncommon. If you put in a new one and still have the one you removed, try swapping the old one back in.

Most of my Cubs start up with very little choke. Much of the time, I pull the choke fully on, hit the starter. In a few revolutions they fire up and I immediately push the choke fully or most of the way open. If the engine is warm, I may not have to touch the choke. The "fully or most" and "may not have to" are individual differences from one tractor to another. My one tractor with a Zenith carburetor is different. It seems to want a lot of choke to start and continues to need some until it warms up. Even then, I usually stall it at least once. Since I only have one, I don't know if it is this specific tractor or if it is the nature of the Cub/Zenith combination. See it here:
https://www.youtube.com/watch?v=dNiS86_H-RA

[millee618]

The cub ran all last year. Had a major oil pan leak so I replaced the gasket and at the same time went thru the oil system and made sure everything was clean and all oil access passages were clean and open. Plug’s were very old so decided to do a complete tune up and replaced everything from the plugs down to and including the distributor components. New oil filter,cleaned and replaced the oil in the air filter unit, new carburetor, and now new ignition oil. Starts and runs good for about 10 seconds starts to sputter and stops. Sometimes can keep it going a little longer by adjusting the choke but still something isn’t right. I need to readjust the throttle linkage from the carburetor to the governor. Trying to find some instructions on how it’s done.

[Jim Becker]

That is beginning to sound more like a fuel flow problem. Check the suggestions in this thread:
viewtopic.php?f=1&t=116606

[Don McCombs]

Tell us about the new carb.