OK guys I decided to do some crazy research because I wanted to build a bike without someone giving me lashings for it. I spoke to the DPS, TxDot, and the Austin PD...this is what I got directly from all of them working together to give me this answer. Based on the laws because it is a gray area what they told me based on the Texas Code chapter 551 it is only illegal "IF THERE IS A CITY ORDINANCE THAT MAKES THEM ILLEGAL IN THAT CITY". So, in Texas there is no engine limit but it cannot exceed 30mph. And every city in Texas it is legal but just don't screw it up in your city to make that city have an ordinance against them. so all you crazy MB don't come to austin or San Marcos because I've already gotten a green light from both. I've also gotten the green light from Texas State university PD.