When I start up the bike the exausts is rich and won´t warm up to a leaner fuel mix/rpm for about 10 min. When warm, runs great with the exception when it has been running for awhile and I come to a stop at a light or traffic, the exaugsts smell rich and the rpm´s are higher than normal. I can somtimes kick down the throttle and it will reduce the higher rpm´s or let out the clutch in first gear a little and it will bring down the rpms. This happens all the time with this bike. I questioned the previous owner who stated he turned down one of the screws on the carb but that didn´t do any change.......Can you give me some help please !!!