Black smoke when revved while cold. Uses oil, but not a lot. Gump suspects valve seal. Bike is an 03 of unknown hours. Buddy bought it about 5 years ago and I got it off him. I am sorta concerned that it is too lean causing blow by at the ring but there is no gas in oil. Hell, could be a dirty filter. Runs strong, starts right up and purrs. Maybe I'm just paranoid.