Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Black smoke not white? No lose in power? Black smoke would be fuel, check the carburetor choke flap to see if it is staying open.
Is oil level ok and not thin from gas in the oil?
Did you find problem?
Not white/grey smoke, which would be blown head gasket? Common problem on the single cylinder OHV Briggs engine.