I am having carb problems with a CM400T. The carbs have been rebuilt and are cleaned thoroughly. When you start the bike it runs great for about 5 minutes. Then it starts to flood out and will barely run at all. If you turn the petcock off, when the fuel level gets lower in the float bowl the bikes starts to run fine. As long as you regulate the amount of fuel in the carbs it runs great. The float valves are new and are sealing properly. The float bowls do not overfill and run out the overflows. We have had the carbs out of this bike at least 20 times and everything is right with them. Any ideas would be welcome.