Interesting. That is the second abduction I am aware of this week. A few days ago somebody posted a question (in Wrenching) about a thermostat part number. I replied and now, that too, has vanished.
Oops. Sorry, I don't mean to highjack this thread. Carry on.
I guess we'll have to blame these anomalies on 'Gremlins' or aliens or a Black Hole or something. Maybe, 'Homeland Security'.
When I rode my Stone Stock, 3000mile old, '87 to Monterey, CA. for the Laguna Seca GP back in April 1988, at speeds of 75-90 MPH from Wendover, UT and back, it got about 42 MPG. With a 18"x18"X36" Track Pack bag on the back. And used some Oil!
Maybe, 750cc in 1600 miles of Golden Spectro 20W50. I switched back to the Kawasaki 20W50 oil after that ride. But, I don't think it was caused by the oil, now.
I'd gotten as low as 35-36mpg, twice in extreme head winds, prior to 2010. (Before Thermo-Bob and oil flow modifications)
I used to get 46-52 mpg average, for most of this bikes life. 0-63,944 miles, that is the mileage my oil flow modifications started. Fall and Winter of 2012/2013.
During the course of testing I had to replace a cracked header pipe, with 2009 header and heat shield. Which required Richer pilot jet and richer needle. (the 22 cent mod.)
I had had 2, 1"holes in the top of the air box for 10+ years and a 142 main jet for 20+ years. I live at 5347 ft. The bike seems to run 'great' from 4000-13,800 feet, currently.