The engine is getting too much fuel. check the air filter. IF that is dirty then it is not letting enough air in. IF the air filter is ok then the issue is with the fuel system and if it is injected, the injectors are worn or bad or if it is carbureted the float is set wrong or sinking. The jets are out of adjustment or the idle and mixture screws are out of adjustment.
Answers & Comments
The engine is getting too much fuel. check the air filter. IF that is dirty then it is not letting enough air in. IF the air filter is ok then the issue is with the fuel system and if it is injected, the injectors are worn or bad or if it is carbureted the float is set wrong or sinking. The jets are out of adjustment or the idle and mixture screws are out of adjustment.