Color me Stoooopid.
The adjustable main jet on the Zenith was set to fully closed! 🙄
Set it to 4 1/2 turns open and she runs super smooth now. Will have to rebuild it with ethanol proof parts at some point, since this Zenith was overhauled in 1970. Still, it’s good fun to pull something off the shelf after decades and have it work so well. Just remember to check the factory settings!
