Starting and running issues

[Darren]

Hello all, I purchased a 2014 GZ250 from a friend that had a few issues. I was able to start the bike and let it idle with the choke/enrichner on but when I shut off the enrichner the engine would slowly rev down and eventual die (about 30-45 seconds). It would also die if the throttle was opened at all. I removed the carb and cleaned it out pretty well. Drilled out the air mix screw cap and cleaned that area as well, it seemed gummed up (I could not screw it in before cleaning) but I reset it at two rotations out which seemed the same as factory set. After I got it all back together it wont start at all. Turns over fine, there is spark and the carb fills with fuel. I did notice that the o-ring around the base of the main jet seemed pretty chewed up, other then that, everything appeared to be in good condition. I did have the air box detached but I wouldn't think that would be an issue. Any ideas? Thanks.