My previously enjoyed 2002 CB500SY had the cam chain tensioner behind the cylinder. It rattled when I bought it & even after I'd done a couple of low miles oil changes. A new one was about £50, so I made the "special tool" from a bit of an old steel plastering trowel & was amazed at the crude design.
It was easy enough to clean & I fitted a new spring from a box of springs bought at the NEC & polished the plunger. The slot allowing oil onto the plunger was supposed to face downwards to catch splash, but I fitted it topmost to retain oil.
50k miles on fully synthetic & 5k oil and filter changes and more than a reasonable use of 10k rpm, almost no short runs below 100 miles and it was still silent when I sold it.
Worst thing was the rear caliper sliding in the alloy carrier - I made brass bushes and oversize s/s pins to cure that - and Brembo pad springs available only by special order from Honda Belgium, via Lings (who were very good). Brembo suggested buying new calipers!
I fitted one of the last Motad full s/s exhaust systems, complete with the joy of extracting the original studs from the head.
One of the best bikes I've ever owned, but only an indicated speed of 119.5 mph available, even down the Mountain.