not getting enough gas

[funnygirl1174]

hi...I have a moskito 125r. I don't use it that often since it is located at my parents summer house. When I try to start the bike cold, it will start right up. Once I have ridden it for awhile, and then I try to start it, it will not. I have determined that it is getting too much air and not enough gas. When you place your hand over the air intake, the bike will start shortly after. Any suggestions on how to fix this?