I took on all that members said and looked into why there are two push rods for the CB500. CB500K0 had part number 22850-292-020 and the rest of the 500's had 11850-323-000. The thing that got me was the rod for the K0 was one piece but, the other model's where a 3 part rod that was pressed together to make one rod.
Had a mail today that explained why this was done. Honda in there wisdom came up with idea that the end of the rods could be pressed on to any length of alloy rod so it could be used on other Honda model's. But, also this 3 part rod became a weak part if knocked by the chain.
I will be having a meeting with a tool maker to find the costs of producing this part again.