Did you try loosening the screws on the side where the round plastic piece is and turning it so the choke flap is open on top of the carb???
Also since it's a new motor it could be a little tight and needs to run at about 2,000 to 2,500 for about a half our.
Shut it down if you need to adjust anything during that time or it has a problem like over heating.
You should not let a new motor idle in the first half hour or so, at least I don't anyway.
Kurt