i have a 1 kva portable genny i can get it to run but not for long about 30 to 40 mins then the plug gets very sooty and black and it cuts out untill i remove the plug and clean it and i am fed up with cleaning it

dave h, November 2010

From what you have said it sounds as if the engine is running too rich
Might be caused by
Incorrect spark plug - Electrode too hard
air / fuel mixture needs adjusting
Blocked air filter
If 2 stroke engine petrol/oil mix incorrect - too much oil - check manufacturers spec

Maurice, November 2010