Ciao isn't working properly anymore?

Hi, so to describe the problem: my Ciao only starts when I run it into it, and when I kick it in it doesn't start at all. It also doesn't idle. As soon as I stop running (when it's on), it turns off. It also doesn't respond well to the gas. It stays on for a while when I step on the gas, but as soon as I slow down, it turns off. There's also always some gasoline at the bottom of the exhaust connection (the exhaust isn't connected at the moment because it's broken), so it's a bit wet.

It's been like this since I overhauled the engine (new gasket, piston, ball bearings). Before that, it didn't run great but it was still much better than it is now.

What could be the reason?