O-Rings between the cylinder block and top crankcase

Hi,

I have a 1980 A2. Can someone tell me if the O-rings between the cylinder block and the top crankcase are required, please? Not the ones that seal the 4 x oil ways but the ones that go round the cylinder base. Each cylinder has three (3) O-rings; 2 x 67mm and 1 x 67.5mm. Please see picture. My bike didn't have these installed and the Workshop Manual does not mention them on Cylinder Block installation.
Thanks in advance,

Andy

LOL. those o-rings seal the cylinder liners to the cylinder block and only accessed if you pull the cylinder liners (sleeves) from the cylinder block. One o-ring is red and goes on the sleeve at the top and 2 black o-rings are on the bottom of the sleeve. Only a few of us have gone to the trouble of removing the sleeves. For giggles you can look up Cylinder sleeves in the search and find my posts about the removal replacement of the sleeves.

LOL yes of course. Silly me