2002 polaris 90

This time it’s my daughters , after it warms up it will not run at full throttle , the carb has been cleaned three times once by a polaris dealer the reed valves are new and I don’t see the head gasket leaking anywhere . The spark plug is new along with the fuel filter . That’s the list , it’s left a ton of people shaking their heads , thanks for any help !

what’s the compression? Also check to see if the fuel line is good (inner wall colapsing). The Chinese may not have the ethanol issues that we have and may not be using fuel line that is made for ethanol in their factories yet. Or they just say that it is even if it’s not, wouldn’t be the first time I’ve seen similar things.