OK, so, I screwed up and wasted a lot of peoples time. I do have an FS90R. It has been stilling cold and forlorn in the back of the shed while I enjoyed the services, reluctant as they were, of the FS80R I was actually using.
Sigh. Age and ignorance are a terrible combination. So, cleaned the new oily plug with some cleaner, pulled the spark arrestor and hosed it off, though it was not bad, I could see thought it. buttoned it up, static set the carb screws and fired right up. Still smoking a bit at idle, but once warmed up it ran fine. Just a slight tweak on the H screw to speed it up a bit.
After some sulking I got out the FS90R, bemoaned dirt and grim, fully expecting it not to run at all, since "someone" left fuel in it last year. Dumped it out, environmentally conscious of course, dribbled in some fresh and pumped the bulb "a lot". Fired on first pull. Well, popped on first pull anyway. Runs fine. So nice I wonder why I was not using it all along.
I had a video of the FS80R running but I cannot upload it, too big.