Could be something other than the carb.
You did replace it with another Nikki?
or a knock off Look alike...
It would be a lot less headache trying to find out what's causing it not running right
than trying to make another work.
Its a knock off I'm in the process of rebuilding the original Nikki .
I just never did like a none adjustable carb that's why i want to try and replace it with a different style
I am a tinkerer and was just seeing if I might be able to replace with better carb