[nate7723]

It is missing a plug

The rod that is visible is what the valve rockers pivot on and is called the rocker arm shaft. There is a plug (BOLT, SEALING (12MM) 12207-MGZ-J00) with a gasket (WASHER (12.2X17X1.5) 90418-KYJ-900) that screws into the side of the engine. There is one at the front of the engine for the exhaust valve rockers, and one at the rear of the engine for the intake valve rockers.

The bolts require a 6mm hex key (allen wrench) and should be torqued to 15 Nm / 11 lb ft. They are accessible without removing ANY body work, so it wouldn't hurt for everyone to check that they are tight.

You should not run the engine until you get a plug in there. If the rod works its way out, the valve rocker could come out of position and you'll end up like this guy:

http://www.cbr500riders.com/forum/honda-cb500x/1536-cb500x-engine-failure.html#post20138

 

[nate7723]

I'm still trying to figure out how his bike "imploded", I don't recall that in the original thread unless I missed something.

The bolt that holds the rocker arm shaft in place fell out, allowing the shaft to work its way out, which in turn allowed the rocker arm(s) to move out of position and stop opening the valves. When this happened, the engine stopped running.