Re: New engine
You said you ran it "for 10 to 15 minutes". I hope you meant you were riding, not sitting still. You have to remember these are 'air cooled' engines and rely on moving air passing over the cylinder head and cylinder cooling fins to run at design temperature. Prolonged running when the bike is setting still can cause overheating. Ride that puppy and don't run it stopped for extended periods.
If possible post a photo of your carburetor and we'll identify it for you.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"