The original Honda faceplates are made of green translucent plastic.
The aftermarket ones…at least from Marcel in the UK are made of white plastic.
So at night the back lighting was too bright as I read on this site. So the fix was to use different bulbs.
Because I was lucky to read that before I reassembled the tach I was redoing, I figured out a different solution.
I found green,translucent,sticky back film. By holding up the original Honda faceplate and the aftermarket one to a light at the same time, dark room, I found it took two cutouts of that film to equal the backlighting of the original.
I have an NOS speedometer mounted with the redone tach, but not on a bike and haven’t tried them. Pretty sure it’ll work.
I’m not saying do this. I’m just pointing out the issue with a possible better solution than trying to work around bulbs.