Don't feel so bad about not being able to work on the saw in a timely manner .I've had some it took me months to finish .
got ya beat Al, some of mine have sat for years.
as for carbon I use a razor blade with a raking angle and a little pressure. some will remain but will get the bulk of it. I use compressed air or a rag or rinse in old gas then a wipe or blast of air to get the piston clean