now these are chinese and reading this forum for a while I know that they use soft metal on the valves. They tighten and you may well need to adjust them.
I would also take plug out and pop a bit of fuel in the bore hole and then put plug in. See if this fires the engine. If this does for a short time it would suggest that its a petrol issue.
One other thing when did you last check your engine oil?
bb
May 2010