RE: Seagull Yak?
On a cowled engine, priming the carb when cold requires either of three methods. A finger over the ventura, soldering the hole in the choke plate closed, or an injection tube aimed into the ventura. The easier choice by far is soldering the choke hole closed.
Remember, these carbs require crankcase pressure impulses for the pump... if the insulator mount only has the port on one side, the carb can only be mounted one direction. Sometimes the carb will be rotated to provide better linkage hookup without noticing the pulse port issue. Some engines once primed will draw enough fuel to run without the pulse port to the pump but they won't run properly or be able to be tuned.