Bandit 400
 

I'm in the process of purchasing a bandit 400 as my first bike. Originally the carbs needed to be cleaned but the owner did that then said it ran good for a while then stopped. He believed it was the fuel valve petcock and took it off to try cleaning. The bike does not start still. It will run with gas being shot into the carbs directly tho. Any ideas what this could be? I have a feeling the vacum petcock needs replacing but I'm not sure. Thanks for any help you can give.
Chris