I just bought a used 2008 Urban 50 with around 1000 miles. It test drove good, but since I´ve gotten it home I´ve had difficulties getting it started, & when I do get it started it will run for a couple minutes, die, and won´t start again. I´ve replaced the spark plug and all the gas, but it still won´t work. Has anyone else seen this same issue & have any suggestions?