BladeZ gas goped problems?

Ok... i went to a swap meat earlier today and found a BladeZ gas, 2-stoke, 40cc scooter for a decent price. He did not have any gas so he was unable to show me it running (probably on purpose). Well when i got it home, i cleaned it off, filled the tank, and got it running (took a LONG time) and found it to be really sluggish... maybe 5mph.And not only that, i had to have the carb open ALL THE WAY to get it runnning. I took it around the court twice and down a hill and then..... it stalled. I havn't been able to get it started since. Any ideas? spark plug? any adjustments i should change? There is a screw on the side of the carb... looks like a air fuel adjustment screw. Should i mess with that?