I am aware of a whining noise whenever I pull away and I understand that this is normal for kawasaki's although, recently after coming from a mud run I've noticed a knocking noise coming from my quad at about 10km/h-30km/h. It's not that loud but it's starting to raise an eye brow or two. Sounds like grinding gears? or something with the drive shaft? I don't really know, if anyone has any suggestions or ideas on what it could be it would be appreciated.

 

Going into mud or deep water is really bad for your ATV...

The knocking noise could be either drive converter's weights on the ramp (worn out), or the crank bearing (worn out) going bad due to water/mud ingestion. Get a mechanic's stethoscope and pin point the source of the noise and start disassemblying.