Just received and installed a Sick Bike Parts fuel value for my China Girl 66cc with an NT carb and I'm very satisfied with the results. The motor seemed to be starving a bit for fuel as I live in a mountainous area and am either climbing or coasting. I had previously had a problem with gas cap venting (the motor would die after 10 minutes or so), but that was solved by drilling a little hole on the inside of the cap. After that I still had this "starving condition" at around 22mph. It would get past that if I went faster. But I usually ride between 20 and 22mph.
I had checked the fuel valve filter inside the tank...but it was OK. A couple of tiny bits of junk, which I removed, but they weren't enough to account for fuel flow. Actually, just opening the stock valve and draining into a container one can see the flow is pitifully slow which is probably still good enough but not when climbing major grades up to 40% (21.80 degrees).
Took it for a ride this afternoon with the new valve...and I'm happy to say that there is no more starving for fuel. Prior to the run I opened the valve and drained fuel into a container and saw the hearty flow of fuel this valve provides! Besides the 2 dollar NGK spark plug, this is the best money I've spent on the bike ($9.95).
Link to the part: