Speedometer

["davidwjones" <davidwjones@cox.net>]

"I've got one on the same subject. Mine will go to about 40 mph and stay
there regardless of how fast I'm going above that. Then it increases
higher and higher even though I am at the same speed. It will then get
to  about 90 mph and then fall back down to 40 again."

That would almost certainly be the gauge. Dirt, dust, fuzz, or possibly the
bearing for the needle or the seat are worn. if a cursory cleaning does not
fix it, I'd send it to a gauge shop.

Dave