A friend of mine recently purchased a new 1200 Bandit. It has 700 miles on it. Recently, he installed a slip-on exhaust, and changed the oil, using standard Suzuki oil. He has begun to notice that his engine smokes when the throttle is closed. I thought that he might have put too much oil in it, but the oil level is good, and the airbox is clean. The only other thing I know that would cause this is a bad valve seal, but this doesn't seem that likely on a new engine that is still in the process of being carefully broken in. Any ideas?