First off, for safety, adjust your shocks for the weight u are carrying. lowering
the shocks do nothing for mpg. too lite of a setting could cause one to lose control and /or causing excessive tire wear and lower mpg from the wheel bouncing up and down too much.
I have a 98 std upgraded to tourer, since '00.
the stock thermostat is a high flow unit, starts to open at approx 180f and fully open at 203f. The stock thermo is best. Suggest u get the factory technical manual.
45 avg mpg at 55mph is normal for a stock bike and approx 32-33 mpg at 65mph/3000rpm. U lose about 1-2 mpg with the oem shield. A smaller shield such as memphis shades hellcat properly adjusted will allow a slight increase. The human body is terrible for aerodynamics.
I will avg 37 to 40 mpg at 65-70 mph going to work stop and go traffic. I've seen 50-60 mpg straight hwy. It takes a basic understanding of engines and tunning to make the Valkyrie better. from the oem there are a lot of compromises to max their profits, just like dodge did for my dakota (presently 5 mpg above epa, better tires should get me another 2-3 mpg). This means they are not getting the best mpg. Depending how $$$ u want to depart with I can let u know what works and what doesn't.
By the way, I've been perusing this site for 2 yrs now, and there is some good things and info and some really, really bad info on this site.
The valkyrie engine is designed for mpg if its set up properly.
www.valkyrieriders.com this is where I've posted for yrs.