Kawasaki 300 4x2 Engine Noise

I have a rattling/knocking noise in my engine at idle and tip-in. Sounds like a timing chain slap or wrist pin noise. It doesn't seem to effect performance or operation. Runs great just doesn't sound right/well and don't want to make matters worse by operating.

Any ideas on what it could be and the cost of repairs? Over the phone, the dealer said it needs an enigne. I think they are crazy.

Thanks, Ricky.