Hello I curently have a ZDZ 50NG, it has the Walbro 76A 321 carb, the problem is as follow:

Its really hard to start, most of the time the only way to start it is with a starter, and even sometimes with a starter its close to impossible to start, the only way was to add fuel to the carburator with a fuel pump outside, that way the engine would start and using the fuel from the tank, the problem right now is that the engine even if you choke it, it doesnt sucks the fuel, i cleaned the carburator already a couple of times, and it never got better, also the engine is unreliable sometimes because the carb adjustment changes a lot, sometimes its lean, then sometimes its rich, very few times the engine has performed well. Some people say its my carburator, that there was a batch of ZDZ 50 with carb problems.

Please help me fix this engine, I'm curently flying it in a PA Edge 540, here is a video of it with that engine BTW, its of the few flights the engine performed well.

http://aerofun3d.com/videos/PAEdge540.wmv