The seat on my 1100 is mostly intact (only one tear at a sewn seam at the front - very common), but the vinyl on the seating area is very dried out and gray, compared to the sides which are pretty nice.
I tried a product from Turtle Wax (like Armor All) and it helped a little, but also made the seat slippery as h@ll.
Some web research indicated that automatic transmission fluid (ATF) might help to replace the plasticizers in the old vinyl. ATF is just a mineral oil with special additives as "seal conditioners" because it's never really expected to come out of transmission.
My seat just drank this stuff up. I put it on thick and let it sit overnight. After wiping down well, the seat is blacker and the vinyl is a little softer, but still not like the sides. I used leather care wipes to clean it off and it doesn't seem to be coming out and staining my pants.
Best of all, it's not the least bit slippery, maybe it's even a little grippy.I'm calling this experiment a success. ATF is also very good for wiping down brake hoses and any other exposed rubber (except tires!). YMMV.
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