Moderators: I'm not sure if this is the best place for this post, move as may be required?
Some of us are getting the "recall notice" from CB750Supply about the suspected inferior cam chain tensioners. To test whether it is really the rubber (or not) at fault, I have started a test with a Honda tensioner and a Taiwanese tensioner, side-by-side, half immersed in used engine oil, in a clear container. (Pictures at 10 PM tonight) If the roller swells or shrinks (or something) on the half in the oil, it will be obvious after a while. The Honda part is right next to it (and has a stuck roller, came that way, so I never used it...) so the position will be consistent?
Here's one thought I have had about these tensioners, to mull over: all of the Tawianese ones I have seen (and a good number of the Honda versions, like the one in this test) have a sharp burr where the square bearing-retainer notch is punched in the tensioner's arm. If this burr is not removed at assembly, the arm will not pivot, or if it is forced to pivot, will tilt the oiling holes of the collar bearing toward the front of the engine. If this happens, the bearing inside will not receive much oil, as the oil splash for this system comes from the slack side of the cam chain (i.e. back side of the engine), by splash, collecting in the 2 horizontally-placed oil pickup holes. If the oil is lean or lacking (or too thin, like hot 10w40 weight, hint...), the bearing can score at engine speeds above 6000 RPM or so. Once scored, it eventually drags or even seizes. This for sure would tear up the larger lower roller. Something to think about?
