The reason why gas is leaking is because you set the float level too low. the bowl is filling up with fuel and the tangs on the float can't fully close the needle and seat.
The carb is flooding over, which is a bad thing.
I kind of think that you don't have the carb assembled right or you have something way out of adjustment.
A fuel line and filter usually does not fill completely up with gas, there usually is a small air pocket in there, and that's 100% fine.
I think you just need to learn how to adjust everything, and you need to know how everything gets put back together the correct way.
You should not be having this many problems unless you totally messed the carb up or installed it wrong (i have seen people install carbs sideways and they wonder why they don't work right).
The bad thing about all of this is that incorrect installation / assembly. leads the builder to think that these kits are garbage. Then they get all mad and trash every company that makes these engines. Sometimes it all boils down to how the engine was installed on the bike, how everything was tuned and tweaked, and how much mechanical knowledge the builder has.
If you slap one no a bike and get it running right away, you'll think it's great.
If you put one on a bike and it takes you awhile to get it running due to incorrect wiring, faulty connections, carb assembled wrong, etc, you'll think it's a pile of junk.
If you ever ride a m.b. that has been built correctly and properly tuned, you'd be blown away at how well they ride and how well the engines actually run.
