Metal wearing noise from engine

[Suzuk400]

I'm getting a loud metal wearing noise from the engine and think maybe the cylinder and piston might be worn or maybe the rod bushings are worn? the quad runs great and has plenty of power! I hate to tear it apart when it run great but don't like the noises I'm hearing! What are peoples experiance on what wears out in the motor?

Thanks

[wykyd450R]

Check your flywheel bolts!! They may be backing out, cutting into the stator coils. I have seen this happen a few times on z400central.