Hi,
If I were you I would just get rid of it and buy a Honda/yamaha or something well known. More expensive but so much better than unknown bikes like you have. There is nothing like a bike you cant trust.
However. Is this a two stroke or 4 stroke engine?
When you change the plug what it is like?
Is it black sooty or covered in oil or is a nice brown colour?
It should seem clean and a nice brown colour?
roger
May 2009