Engine knock?

[naskie18]

How tough/expensive is it typically to chase down and get rid of an engine knock?

My buddy's looking for a bike, and one of the ones he's looking at the seller says its got a knock, so I'm just looking for some ideas as to what it may be and how expensive it'd be to fix.


Thoughts?

[The CyberPoet]

A knock can be anything from dirt cheap (valve adjustment) to extremely expensive (new engine because part of the piston skirt is broken off and the piston is slapping in the bore).

Cheers,
=-= The CyberPoet