I have a 1989 gs500e and I need a new rear master cylinder. and so far I have not been able to find one anywhere.  If someone can help me I would appreciate it

Do you need the whole master cylinder assembly, or just the "innards", or what?

I ask because on this Ron Ayers page the whole cylinder assembly (item 1) costs $107.02  

But the piston and cup set (item 2) only costs $16.14  .

You can check on other individual parts as well, of course.

i need the whole thing, i went out to ride yesterday, and the whole thing was missing.  For the first time I left my bike out of the garage, and the master cylinder, battery, air box, and guage cluster came up missing.  The cops are on it right now.  There are a few other gs's around here so I will keep my eyes open.