Jason,
I got my first Standard 88 VR in 91, it had 1,600 miles on it. After it got broke-in I got 47 mpg at highway speeds with the Cruise on, my buddies VR only got 42 mpg. In the three years I owned it the milage stayed the same, it had 33,000 miles on it when I sold it.
My current 88 Standard VR (both were Salt Lake Silver/Gray) had 48,500 when I bought it six years ago, it now has 111,700 miles. The best mpg with this one has been 37 mpg at highway speeds with the Cruise on. I'm now getting 33 mpg. From day one with this bike the pipes would always have about a 1/8 inch of soot on the ends. The Plugs have always looked good and are a light tan.
I checked the diaphragms and all four are cracked. I'Ve got the diaphragms and slides ordered along with a K&N air filter. After these are in I'm sure the mpg will increase back to my normal 37 mpg.
Sooooooooo after that I'll keep a close eye on the plugs and MAY do the Needle Shim Mod. I sure would like to know why my first VR got 47 mpg though.