I have a 2005 Honda TRX 250 Four Wheeler and it only starts sometimes. Why?

I changed out the oil, spark plug, and took the carburetor out and cleaned all of it. It starts sometimes and sometimes it doesn't. When it does start, it may turn off unless you give it gas or very few times it will stay on but ride a little rough. I know that you should let the carburetor warm up and stuff, I have taken the air filter out too and cleaned that as well. I don't know what else to do. I mess with the throttle body sometimes for it to stay on but I don't like running it on full throttle and even that sometimes don't work. Any Suggestion?