Dirt Bike bogs down after 5 minutes?

My son has a 2016 Tao Tao DB 114 dirt bike. It starts with one kick on choke. I then turn the choke off and let the bike idle. It idles great, nice and smooth. Then after about 5 minutes it bogs down and dies. Then will not start at all. When I kick start it, I get some resistance or push back from the kick lever. And it will not start at all.

If I let it sit for a an hour or over night, same thing. Starts nicely and then bogs down.

I have changed the spark plug and the fuel filter. There seems to be fuel flowing. I have a new carb, but have not put it on because I m not convinced that s it. There is an idle adjustment on the carb, but no mixture adjustment. We have a second bike like it for his twin. No issues with that, so I m not sure if it is a gas issue, as we have used the same fuel for both. Or at least I assume. Is it an air mixture issue, bad gas, fuel flow or carb issue?? Thanks for your help in advance!!