Aïda,
We had tons of grief on the '80 R65RS when we firt got it. Seemed like every other time Suraklyn took it out he came back with wet-boot syndrome. I went through needles, new floats, lapped the seats, etc - no good. I finally pulled the worst offender and decided to clean it real good. When I put some pressure to the needle seat (blowing back upstream) a bunch of hard black granules blew out. I then took off the other carb with like results. After this, no more leaking. I am taking a WAG that the little hard black granules were decomposed fuel line...