My sons buggy won't run it coughs and splutters but won't actually run it is a Chinese thing 125 four stroke

Hi, dont know if this will help, but i have found on a few of these chinese engines that the woodruff key inside the flywheel sheers off, this sometimes still allows it to show spark at the plug which fools you into thinking that you have a fuel issue and leads you away from the actual fault, hope this helps
jim (renault truck mechanic)

Sounds like it may need some carburetor work. If you've stored it without any fuel stabilizer added, mixed well, and ran through the carburetor a little, even for as little as 30 days, the fuel can break down and leave deposits on the small mixture jets inside. Spraying some carb cleaner while starting and running will sometimes loosen up those deposits, but more often than not the carb will need to be taken apart and cleaned.