Whenever I take off from a stop at 3500-4500 RPMs the clutch makes a chattering sound and feels like it is not engaging smoothly at all. Is this normal? The bike was ridden pretty sedately for the 2600 miles it had before I bought it, is the clutch worn or damaged in some way? Is there something I can do or replace to fix this? If I don't do something about it, will it break something if I launch it hard?