Remote Needle Valve, or Standard?
I have 3 2-stroke O.S engines with remote needle valves. I have not had any trouble with any of them. One thing that I am surprised that I haven't seen mentioned here in reply to this posting is the use of tie wraps. These are generally used to keep wiring together. I use small ones to secure fuel lines to the brass tubes that come out of the fuel tank, then to both ends of the fuel filters, then finally to both sides of the needle valve and then to the carburator. This really ensures no air leaks.
Jeff