It's hard to imagine the kind of world forum "experts" actually live in sometimes. Along with the myriad of nonsensical advice, they seem adamant that no force should be applied to the CB500/550 cam chain adjuster during an adjustment episode.

Strange, this. On at least two levels. First, compare the inclusion of a screw slot in this model's tensioner, just like the tensioners in many earlier Honda models, with the absence of a protruding screw in the tensioners in more modern Honda models. Hmm. Second, it seems inconceivable to me that, once you have observed the rack and pinion design of this tensioner, made of stamped-out sheet metal prone to binding up from rust and inherent flexing, that you could come to any other conclusion than that it will need help. And it does, as anyone who made a living working on these bikes well knows.

A short, stubby flat blade screwdriver is needed. Since Honda incorporated that into the actual special tool dedicated to adjusting the valves on this engine, it seems a natural. A long open-end wrench completes the tooling that will get this job done. With the engine running (only the 500/550/650 cam chains are adjusted running) one simply loosens the 6mm locknut just enough to free the screw, and then the valve adjust tool is used to apply counterclockwise force on the screw until any cam chain noise subsides. Before releasing pressure, the locknut is snugged up.