My friend has a motorcycle that makes noises when at low speed in first and sometimes second gear. Its a similar noise to that of a bicycle changing gears, that "clackity" type noise. It doesn't always happen, and when you get going past 10-15kph it always stops. You can't feel anything going on and from what I see the chain seems to be moving too quick to be making the noise as the "clacks" are fairly slow, but maybe i'm wrong. Anyone have any ideas what this could be? The chain has also been cleaned and lubed recently.