05 800b unbaffled stock pipes, grampsized, K&N filter, 50 pilot jet, 138 main jet, Dynojet needle on 4th ring from top, and 17/41 sprocets. Mostly 2up riding between 60-70 mph. 45-48 is normal. This orcording to the odometer and amount to fill tank. The spedometer and I believe the odo are reading fast, so actual will be slightly less. Alot of hills in this area as well.
However, rick is correct about odometer. I can't be certain about how far the speedometer is off, but I am certain the odometer is 5% "long" - given the nearly new 140/90 Michelin COMMANDER II currently mounted on the rear (different rear tires at different levels of wear WILL effect the odometer reading).
This would make "actual" results (when compared to another vehicle with a dead on accurate odometer) to be approx. 47.25 to 47.75 mpg.
GRIFFJO Montani Semper Liberi
2003 Vulcan® 800 Classic - Pearl Mystic Black
National Cycle Custom Heavy-Duty Windshield
Mustang Two-Piece Wide Vintage Touring Saddle
D2Moto SissyBar/Backrest - K&N Air Filter
Viking Quarter Circle SaddleBags & SissyBar Bag
Highway Sprocket Set (18/40 - 2.222:1 ratio)
Baron 3" Bullet Tachometer - Engine Guard (black gloss finish)
Michelin COMMANDER II front 130/90-16 73H, rear 140/90-16 77H
EK X-Ring Chain, BackOFF® Brake Module & Deer Warning Whistles
I filled mine by hand, on the kick stand, to the brim. Rode 121 miles and refilled by hand with two gallons. Maybe it's because I was riding country roads at 50-55 mph with 60 mph on some straightaways. 2012 900 Classic SE with windshield. Am very please with mileage.