The speedo on my 81 1100 was one of the 85 mph ones.
After it died a horrible shrieking death on the way home one night. I changed it out with a 140 mph one from an 87 gl1000. With a couple of nut extenders to help with the mounting, the speedo mounted right up.The new (to me) Speedo is accurate to within 3 mph which is better than the original that was off by 6 mph.
The onlyproblem is 85 and 90 mph don't seem as fast now with the different scale so I drive faster.