the miles really won't matter Garelli super sport XL has that much or more and runs good. mine also has a leak in it too. i just turn the gas off when it sits. you probly need a rebulid kit or clean the carb up well to stop the leaking. all mopeds smoke. you might needs a muffler. i'm not real sure, but i think the mopeds do need some back pressure to run well. it will run with out a muffler but i think it would be better to have a muffler. the $40 daller deal is up to you. i payed some guy to fix my carb and some other stuff. he didn't do such a hot job on it, but it runs thats what matters to me right now. hope i helped you out in some way.