Craftsman 29000 30 in. Riding Mower Engine Sound

[forna129]

New Craftsman 29000 Riding Mower engine question
Sears just delivered my new Craftsman 30 inch riding mower Model 29000. Starts up fine and runs okay. Doesn't stall. However, the engine sound is not steady. Instead it has a rhythmic wah wah wah sound which is constant and at all speeds. Could this be something which fades as the engine breaks in or is this a carburetor/spark plug issue? Thanks for any help. Will call Sears to check it out if I can't find the answer on my own.

 

[mechanic mark]

Post model number from under seat, engine manufacturer as well as all numbers from engine, thanks.

 

[ILENGINE]

May be a carb issue, but could be related to air temperature since the new engines are calibrated to operate at above 70 degrees. Normally will surge until warmed up, but I have seen some that wouldn't quite smooth out in cold temperatures.