RE: engine not starting
Im with Mecano. if you have low compresstion the engine wont run right or at all. if your coil readjustment dont help check your air filter. if it is to wet or really dirty it wont pull enough air thru the filter there for low compresstion. easy way to see if it is you air filter is to take it off and pull it over and see if there is a differance if so then your filter is plugged. clean the filter and put it back on and you should be ready to go.and you say the plug gets full of black oil and soot.... well sounds to me you have a lot of carbon build up on the top of the piston. that is from using cheaper 2 cycle oil and running it rich.