[Slo'Poke]

When I owned a 650R, 5K was adequate for my purposes. As it's been said, you don't want to 'lug' the engine (ie - run it in a gear where it sounds like it's struggling), and my normal cruising speeds was in and around 70 mph. High 40's was a typical mpg at the time.

Nowadays, on my VN900C (no tach), my strategy for maximizing fuel efficiency is to use 20/30/40/50 as shift points, and still use 70 mph as normal cruise speed. I average mid-40s street / low-50s hwy.