It could be lean or rich. Most new engines i get have the LSN set so lean it will start but quit when the throttle is advanced.

How does it sound when it quits? If it gurgles/hesitates ect with an extremely slow advance of the throttle then it is too rich. If it bogs out, then it is too lean.

Also try the LSN pinch test if you wish. It won't hurt.

Pinch the fuel line 1/2 inch away from the carb too kill the engine. If the engine quits in 0-2sec then its too lean. If its over 3 seconds its too rich. 2-3 seconds will be in the ballpark. This is just to get you in the general area.

Once break-in is complete, tune to sound and performance Only.

Ryan