i have bought a new engine kit 4 stroke rear mount from livefastmotors.com and i have a 2007 specialized bike extra small and i realized on the back thatyou have to have the big bolt not quick release so i just said **** with it i should use a new bike because my specialized is really worn because i use it for stuff that there enduros one of the most top of the line mountain bikes that specialized makes is not meant for so i really am rough with it and i dont really take care of it cause anyway i wanted to start over can anyone tell me a bike to get under 500$ that has a big rear axel bolt sturdy frame high quality just a great bike for the rear mount huasheng 49cc 4 storke engine kit please tell me thank you!!!!!