bad flywheel question...

[jcs003]

how would you know if the flywheel is bad?

i heard if it has a rattling sound its bad. is this the only way to know?

[Honda 250r 001]

Rattling will mean the magnets have fallen apart inside, and yes then its junk. Unless it looses its magnetism there is really nothing else that can go wrong with a flywheel. (as in normal wear and tear)