Engine noise when hot

[What]

Hey guys, new here.
Need help figuring out engine noise after warm up about 10 minutes+/- from a cold start. Starts fine and idles good but after warm up it develops a noise and starts running rough. I've synced the carbs, adjusted the valves, did the cam chain tensioner and changed the oil. After it cools down its back to normal. Would the cam chain or the tensioner change after getting warm? And then cause the timing to change making it run rough. All adjustments made per the manual. Anyone else have this problem? Thanks in advance.

 

[Rod]

What is the year and model of your bike? How many miles on it? Has it ever had any major engine work?

 

[What]

1972 cb750 26,000 miles. No major engine work that I know of. I got a compression tester.
#1 150lbs
#2 150lbs
#3 145lbs
#4 125lbs
Took it for a ride. Only makes the noise when the engine is unloaded. With a load on the engine it runs great. Noise is usually at lower speed. If I hold the brake with it in gear while slowing down, I can make the noise go away. Sounds to me like a valve train clatter. Not sure if anyone else has had this issue. Thanks

 

[cfairweather]

Prior to adjust the timing chain, first set the timing mark to the "T". Then loosen the adjuster bolt. If you press on the adjuster shaft with a short screwdriver through the rear shaft hole, you will be able to tell if the shaft is applying tension to the chain. Without the screwdriver inserted, tighten the lock nut. The spring should apply the correct amount of tension. The OEM timing chain tensioner system is a weak point in this engine. Cycle-X sells a better unit that is very quiet. Also, I would use 20-50 oil in the CB750. The oil pressure will be a bit better with 20-50 vs 10-40 when it warms up. Can you make a video so we can hear the noise?