If not already see if it’s routed above the left tank mounting lug.
When I altered mine to that route it seemed to help, and I think my old one was back in the 1970s.
Regards Jeremy
Jeremy, can you inform us exactly how the clutch cable is supposed to be routed?
I will check later,but I am sure it goes from the lever ,round the headstock,under the RH tank mount,through the hole in the frame next to the coils ,down between the 2 LH carbs,rubber mounts and onto the final drive case,.
try that ,keep the bends as wide open as possible ,the larger the diameter,the better
.