Hi Craig, your help was precious. I had the cable holder in place, just the last owner changed the cable using a very bad route and forgetting to use the cable holder. He did some other very bad works, so I have to be cautious and check every bit.
Just for future reference the cable passes the cable holder

runs between the tank and the main tube of the frame on the right, crosses under the tube just before the throttle cable, passes under the left side of the tank quite far from the back exhaust

Now the bend is very nice, the cable is totally free and can be moved backward and forward without any resistance and the clutch may be operated by an human and don't need Godzilla any more. The clutch is better in the SSD than in my 450 scrambler, so I think to change the clutch cable and find the good passage in the mono.
Now I think I have to check the tachometer cable of the SSD, since I noticed that in extreme turn on the right it goes in tension and moves the tachometer, I'm sure the route of the cable is incorrect and if not fixed it will broke. If you can supply any info please do.
Thanks. Yeh, photos would be good. Don't suppose you got the frame and engine numbers by any chance?
Yes I have the frame and engine numbers, I'll PM you with data and photos
Ciao
Giovanni