I have a new 2010 yamaha FZ 16 motorbike at 1,500in mileage. Since the beginning the carburetor has not performed normally. It seems that the air and fuel mixture is not right. The engine stalls frequently when or while the engine is cold or just started, and even when it is already warm or hot and running, especially when I ride slow between 20 to 40 KPH, that I have to pump gas and switch to a lower gear as the engine tend to stall or die out. At mileage 500K, I took the bike to a yamaha dealer for its first warranty check. I pointed out the problem with the carb and the mechanic thought that there is water or gum/dirt in the carb so he opened and cleaned up the carb. I didn't see any water nor anything that came out as I watch the mechanic "overhauled" the carb. He adjusted and calibrated the mixtures and everything but the problem remains until now. Do I have a "lemon" carburetor here or what? Please help me...