Dear Dan,
Thank you for being patient and writing me about my problem.
I really didn't write about my problem on the forum without reading first the previous 11 pages related to the Beta clutch.
So, I followed all the possible solutions described and only when I was desperate I wrote the question.
The lever clutch has a gap (the piston is free).
When I put the disks I checked the gap that should have in the center of the clutch. It almost had NO gap at all.
I tested the bike and do the same.
After, I reopened the clutch and I took out one, the thinnest, of the two washers that are on the bearing.
When I tied the clutch, it had a gap. I tested the bike and it was improved on the 5th gear (not completely disappeared) but it is doing the same on the 6th gear.
DESPAIR!!
Should I check the clutch pump? (on the carter)
Is there any risk now that the clutch has only the one washer inside?