I just rebuild my XR600R. I'm having trouble with the carbarator overflowing. Before I start the bike, no problem. It only overflows after it runs for 10-15 minutes. Than won't stop flowing out the overflow drain even after the bike is off. I've had it apart twice to check the needle and seat. The fuel flow shuts off completely with light pressure. The dry level is correct @.53". Can the float on a 94 XR600R saturate? How can I test it? The float and needle are pricy. What's next.