White or gray smoke is caused by oil burning. Black or dark colored smoke is cause by to much fuel/burning rich. I recommend checking the oil level. If the engine is over filled you need to see if the oil smells like gas. If the oil smells like gas, the carburetor is not regulating the fuel to the engine. If this is the case, I recommend cleaning or replacing the carburetor.
If the oil level is fine and the oil does not smell like gas the choke of the carburetor could be stuck in the on position. When the engine starts and you take the choke off the engine should smooth out. You can check the owners manual for adjusting the choke.
I the oil level is low and the smoke is gray I would suspect a blown head gasket. I recommend that a service technician replace the head gasket because of the special tools need to properly do this type of repair.
If you need more assistance, we will gladly help please submit more information.
Here is a link to order any parts you need.
Sears Parts Direct
If you do not feel confident repairing this problem yourself, then you can have it repaired at your home by a Sears technician. Here is a link for the website:
Sears Home Services