Vintage BMW Motorcycle Owners

R60/2. Previous owner rebuilt the top and back in 2007 including sending the heads off to be rebuilt. No idea how many miles he put on the bike since the rebuild. When I got the bike a couple of years ago it was already showing some low compression and oil usage. So this winter I thought I would at least pull the top end and go through it. So far, other than the obvious burning of excess oil, things don’t look too bad. Hopefully the cylinders aren’t excessively worn and I can still go with stock pistons and rings. First three pictures are the left cylinder and the last three pictures are the right cylinder.

Hi Kurt,
Everything looks fine. You can even see the honing marks.

If I were you, I would buy honing stones, connect to my drill and perform an easy renewal of the honing (use a correct oil solution for this). Then clean the heads and reassemble (It is of course better on this occasion to use new piston rings).
Before assembling, insert a piston ring into the bore, and with a filler gage make sure that you are in the correct specs.

Hey Kurt, In the future if you have low compression try to get a leak down test to see why.
From your pictures my impression is it is not rings. When I have had leaking rings they will start to clean the face of the piston starting at the edge. Your pictures show a carbon coating all the way to the edge of the pistons.
I would check the valves and guides for the low compression and oil getting by the guides. Also looking at the pictures it looks like oil may be leaking from the oil return line at the bottom of the cylinder/head on the left cylinder.
I would still pull the cylinders to check everything I could and hone with new rings.

Jim.