yx 150 problem

[theconister]

I can start the bike properly checked timing every think the head has been off found chip in the cam so replaced that but still have the same problem from when i bought the bike it pops back fire wen i rev and some times cuts out and it has no power it has a lighten flywheel on it but all i can think is it has to be a carb problem or that lightend fly wheel but i have tryed 2 different carbs but off a smaller engine pit bike i dont know what problem could be ? Its a yx 150cc engine