My daughter's taotao 125 atv has been running good up until yesterday. I replaced the carburetor and air filter. The vent tube from the engine just vents out to the side of the motor. Yesterday it started smoking and sputtering what I assume is oil out the hose, after she rode it for 20 minutes or so. I'm looking to find out what issues I may have. Only thing noticeable so far is the spark plug was loose and won't tighten. So it needs to be replaced. What are some other possible issues? Thanks for the help.