Noise from transmission/clutch 81 (K)Z1100 A-1.

Hello!
I've owned this bike for over 30 years. It has now close to 200,000 km or 125,000 miles on it.
The engine has been apart twice since I bought it.
Over the last 5-6 years I've noticed a squeking/whining noise coming from the transmission area.
It's present from take off in all gears. I can hear it really good riding at low speeds with a load on the engine/transmission.
At high speeds I'm not sure if it's there because of the wind noise.
When I engage the clutch it goes away.
I have changed the front bevel gear case with a used on with much lower miles on it.
Last winter I split the engine and changed all the bearings in the transmission.
Noise is still there.
Any helps will be greatly appreciated!