Brand new Coleman ct200u-ex doesnt always start and turns off. Help!

[ango]

I just purchased a brand new assembled Coleman CT200U-EX mini bike. I have been wanting one for years. Anyways after about 3 hours or so of riding since my purchase, the bike is idling rough and doesnt want to start at times. I can start it with the choke then lay off the choke, which then sounds smooth but then it dies after about 1 minute or so. Its putting out some black smoke. I can see on the valve cover its a bit discolored now. I don't know if its getting hot. I tested the spark plug (it has spark) and then changed out the fuel and oil. same thing. I took off the round ball (gold in color to check it) but its clean. I don't know what is happening. I am attaching a photo. Any help would be appreciated. Im about to return it to the store. Im new to this.

It takes a NGK CHDY F7TC spark plug. But I cant find it at my local auto parts store.

 

[DAMIEN1307]

It takes a NGK CHDY F7TC spark plug. But I cant find it at my local auto parts store.

NGK BP7ES, or if it needs a colder plug, NGK-BP5ES, are the actual NGK numbers that replace the Chinese F7TC plug​

I would go with the colder plug on that one...Be sure to gap it at .025 thousandths.

 

[Wrench]

Bump up the idle. If your carb isn't adjustable thanks to the EPA adjust the Idle at the throttle adjustment barrel

 

[Wrench]

I just purchased a brand new assembled Coleman CT200U-EX mini bike. I have been wanting one for years. Anyways after about 3 hours or so of riding since my purchase, the bike is idling rough and doesnt want to start at times. I can start it with the choke then lay off the choke, which then sounds smooth but then it dies after about 1 minute or so. Its putting out some black smoke. I can see on the valve cover its a bit discolored now. I don't know if its getting hot. I tested the spark plug (it has spark) and then changed out the fuel and oil. same thing. I took off the round ball (gold in color to check it) but its clean. I don't know what is happening. I am attaching a photo. Any help would be appreciated. Im about to return it to the store. Im new to this.

It takes a NGK CHDY F7TC spark plug. But I cant find it at my local auto parts store.

Brand New - It's under warranty, take it back and have it fixed. Ask them what's wrong

 

[Chainlube]

Check the nuts holding the carb on, one or both may have come loose causing an air leak.