I have rebuilt several of these old motors. One can be seen on my blog at: https://conductorjonz.wordpress.com/category/misc/page/2/
They have very hot spark…so don’t be surprised if after cleaning the carb and ignition points she takes off on the first or second pull. The carb is odd…but straight forward. By the way I broke a glass filter bowl on mine once and found a direct replacement at Tractor Supply. 😆
I think the round panels were for a remote control set up. Note the steering bar-type little handle on the rear?
I still have three of these old girls. One SD10 (that found its way into my truck at a meet by some stealthy members of the MOB chapter who knew my enjoyment of these things), and SD15 (Which won Best Restored Antique Motor at a meet last fall.) and a nice original SD20 with its original Tall Boy fuel tank.
I frankly don’t get to run them enough! Really nice runners!
Greg