Take it from a serger expert, sergers change your sewing. Here are a few serger sewing tips gained from twenty years as a serger sewing instructor. Matching the size of your serger needle to the weight of the fabric to be serged is one of the basics. Light fabric requires a finer needle.
Heavy fabric requires a heavy, or larger, needle.
Fine serger threads require more serger tension, while heavy serger threads require less. It flies through because the disks that produce serger tension are far apart. Try the test again with the serger tension in the middle of the dial. The serger thread is harder to pull. It will be almost impossible to pull the serger thread through when you have the serger tension at the highest.