Engine Trouble 80cc motor spitting and sputtering

[LAZYBIKE]

i have a 80cc motor and was running great for a few weeks. now it is spitting and sputtering, no power and shuts off, can anyone tell me where to start beside checking the gas, could i have blown a piston ring?
HELP PLEASE

 

[inspectorcritic]

I notice when breaking in an engine by adding 2 extra ounces of oil that the motor stammers and falls over did you forget the fuel mixture. I think I paid 8 bucks for rings yoou can get them cheaper ebay 2 bucks you got to find the 2 kiss buttons leave at least 2 head bolts on to alighn it to slide back on and note the rings first have a notch half I presume for up and down you dont want put them in upside down put those to the kiss button also check your piston could be that they put the thing in backwards so kiss button is up front that means its going over the exhaust port which is about an inch and the ring can excpand snag the edge and break off a piece of ring slowing you down so in that case turn it around. Maybe thats it always thousands of things to look for got to have vaccum eyes note the smallest details on them shanghai bikes.