Thanks, I kind of understood some of it.
I just fired up one of my K301 and it did the same thing. So, I think it is a temperature issue.
I inspected the carb a second time. Looks like someone might have made the small holes in the sides larger when they were cleaning it before.
There are no adjustments on the carb. There is a brass plug on the top of carb, nothing adjustable.
It runs fine after 5 minutes of idling.