Hello everyone, a couple weeks ago I bought a '05 NE5 with 87 miles on it and in mint condition. the owner has two other whizzers and his wife urged him to get rid of one. after checking it out, i got it home and rode around a bit. the next day i was adjusting the idle and air intake screws and that's when the problems began. sometime during a short ride, it began backfiring and then ran very loudly. i later found out that i lost the baffle from the muffler and that made it lose back pressure. i installed a new baffle and it runs better, but still backfires. i've replaced the spark plug, but to no avail. it runs, but quite rough. Any help?