New Craftsman 29000 Riding Mower engine question

[forna129]

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, thanks. Check engine oil level before every time you mow.