[davepl]

A piece of 1" PVC lawn sprinkler pipe or similar works if you don't have a stethoscope. Don't get your hair/tie/etc caught in the belts!

Really does sound like something squeaking or rubbing, like shift linkage, exhaust, that sort of thing. I don't know much about flywheels, but I wouldn't be tearing the motor apart on account of it until you know what it actually is!

Does anyone think there should be "more" oil up top? Every time I ever ran an engine without valve covers it was a smoke show! But I don't really know. I can see oil in the rockers, so they're not dry. Maybe they're just set right and I'm not used to that :-)

Can you hear it out the end of the exhaust pipe at all?