Weights on a handle bar? Sorry I'm not an expert. It just caught my attention. I'll see if I can find the PDF file I have for the R100 

Never heard of them, might have been used as vibration dampers, might want to check front wheel balance.

Are there threads inside? Do you have heated grips? If you do be careful with the wires. I just got a 93 R and wanted to put dampers inside and use different weights I have but upon inspection it looks impossible 

If you have ever installed bar-end mirrors, it's just like that. There should be a counter sunk, hex head bolt centered in the part of the weight that protrudes from the end of the handlebar. There will be a threaded insert that goes inside the end of the handlebar. Put the two together and tighten the bolt to compress the insert inside the open end of the handlebar. Usually, there is an elongated rubber grommet that is compressed to expand inside the bar to hold the assembly in place. Also like a bar end mirror, you will have to make a hole in the end of rubber hand grip to fit the insert.  There are no pipe threads inside the handlebar.