Check the oil color. Make sure it's not burnt or full of particles. The fuel should be fresh if it is gonna run at all. There is a 12mm bolt at the bottom of the gear case. Loosen that just enough for a drop of gear oil to escape. It should be golden colored, and NOT black. Other than that it should run around 35 mph w/ no issues. It should also idle all day long. Test ride it, and just let it sit running while you "haggle". If it stalls out??? 50.00 off the asking price. another 50.00 just for the heck of it, and 50.00 more just because it's a Kymco.