hi,i have a DT50MX im having some problems with new parts on it can someone help me?

Hi Kid, ok first things first, you say you have put on a new carb cylinder head and barrel is that right? So what is it doing that it shouldn't? The more info you give the more we can help but without all the info we're just guessing. So start at the beginning, why did you put this stuff on? and go from there.