OK !
a chinagirl.
Al.Fisherman and a few others have wrote up complete diagnostic threads you would find very valuable...
Best to read them, then you get a real education, which you WILL need, as operator of one of these machines!
...You will find the advice to 1st disconnect your kill button wires untial all other diagnosis is completed...
Then, pull the plug and check if it's wet with fuel.
If it IS, have a friend help you hold the rear of the bike up and turn the back wheel, and see if the plug is sparking when removed from the engine. You will need to ground it against the cylinder head while turning the engine over.
The factory plugs are always suspect. Replace it with an NGK.
Review those threads for more info.
Good luck
rc
Don't worry abt the piston for a while... lol