Your two 611VA's look good, like not much used. There isn't much info on the earlier Solo's, and some of it is contradictory. Part of the problem is that Solo used 611 for the earlier twin as well as for these single cylinder ones. One source says the 611Va dates from 1967, another says from 1976. I've had two, one red one orange. Believe the earlier ones came in orange and black, until a company with name also starting in "S" complained. My orange one has serial number 20xx.
Sprocket should be .325. There's only one 8mm bar stud. There is a screw at the top of the side cover also, and maybe a long screw towards the back of the side cover, before cover can come off. My 611VA has a Solo 6900249 bar on (that is the Solo part number for the bar). The lever on the side cover is for the adjustable oil pump.
Carburetor linkage is a pain to work on, so getting to carb to clean it is not easy. Cleaned carb on the red one recently to then sell it as non-op, buyer later had it running.
A bad copy of a 611VA manual is at
http://www.solo-germany.de/gba_download/gba_archiv/gba_auswahl_ie.html
Look down the list for "motorsaegen/chainsaw/...", then "alte dateien/old files" under "610VA/611VA". It's in German.
There was once an 611VA IPL online in German, don't know if it would still be there. Couldn't find it again.
