.

>Sounds to me like maybe one of your valves has bit the dust.  Probably
number
>3 exhaust valve.  Let us know what you find when you pull the head off (it
is
>probably not going to be pretty).  If it is #3 exhaust valve then this is
>usually due to overheating.

My friends 74 westy experienced a noise that resembled a rod knock.  After
taking the head off, I noticed a big 'ball' of aluminum stuck to the top of
the number 4 piston.  Along with this, divots in the piston and combustion
chamber.  Too much timing, not enough deck height.  Don't really know you
managed to get aluminum chunks under the valve cover.  Hmmmmmm........