Did you say a remote needle valve? Is there a needle valve that came with the engine that is attached to the carb in the normal fashion? I have seen some really strange problems that crop up when using the remote needle valves that so many have become infatuated with. If you have the traditional needle valve assembly, try using it and see if your problem persists. Also, does it seem to matter how much fuel is in the tank when this occurrs? If you have a tube extension in the tank for the vent line, you may be blocking the vent action with fuel, causing the carb to stop drawing fuel (pulling a vacuum in the tank). Try this with only 1/3 tank of fuel and see if the same problem is there. It may be just a plumbing problem.

Bill, AMA 4720
WACO Brotherhood #1