The question has been dealt with here before: in the CB750, when you go over a bump, or apply the front brake, a "clunk" is heard. By shaking the caliper with the hand, it is possible to reproduce the sound. The reason is that there is a little play between the caliper holder and the bracket where it rotates.
Honda issued a technical bulletin back in the day. The solution was to shim the free play. There was two different washers -0.1 mm and 0.2 mm if memory serves me- and the procedure was to install either, both, whatever it takes to fill the tiny gap.
Long time ago I bought one of the washers -the other was not available- and was planning to do it when the time for brake pad change come. Well, my brake pads were not too worn out but I had to replace the front tire, long story short, let's change the pads now and save some time in the future at the expense of some brake pad remaining.
Sure enough, I couldn't remember where did I put the shim washer I bought! I searched and searched but couldn't find it. And I knew that there would be no better time to stop the clunk than now, because when the washer appears, I won't remove everything again to install it.
What I've done is to use one of the inexpensive feeler gauges I have. I have three or four sets, one of them is very good, with many thicknesses, but this one was cheap and had not many. I just checked until I found the one that fit better, then I cut it to size. Making a hole with the drill is almost impossible without destroying the thin sheet, and so I used one of those punches used to cut rubber or gasket paper. I know, a donut-shaped gasket is a much professional fix, but hey, I think I can live with this.
