I've read in many places, including journalists reviews, that the gas gauge on the AK goes down VERY VERY rapidly. If your gauge is flashing then the best thing to do is go ahead and fill up just to find out how much you actually put in. And then use that information to adjust how far you can go on a tank. All USA AK 550s should have a 3.9 gallon tank. If you put in 2.5 gallons you are getting about 54 mpg and you should be then able to go over 200 miles on a tank, but only if you intend to run it dry. If you put in more than that you are getting less mpg than that. Either way how much gas you put in to fill the tank will tell you what your mpg is. All new scooters/bikes will improve mpg over the first several hundred, if not first several thousand, miles. My last brand new bike was a CTX1300 and for the first 1500 miles I was averaging only 40-42 mpg. But it kept improving the more miles I put on it. After 8000 miles I was getting around 48-50 mpg regularly. And that was considered really good for that bike.
I always use the A trip meter to tell me when it's time to get gas and don't go by the gauge. For what I have read on the AK 550 I would expect somewhat over 50 mpg and likely near that 52-54 mpg mark if you ride conservatively. Lower if you ride aggressively (48-50). During the warm summer months I often get 58-62 mpg on my Burgman 650. A bigger engine but the same size tank. My last long trip included some Interstate speeds and I still was able to go as far as 209 miles before I could stop to fill up. I ended up putting in 3.59 gallons in that time. I don't usually go that far but knew that I could based on my experience with the bike and how it was running. I would expect to do AT LEAST as well on the AK 550 when I get one.
Tested it out just as advised...even filled it up at the same spot to be sure
Both times it worked out to be getting well over 50. Right where you said it should.
I think maybe i didnt have it filled all the way the first time like Stig was thinking. That or i reset the mileage while i was fiddling around with all the neat new buttons and switches on the new toy
What you read about the gauge seems to be the case for me too...Stays on full for about the first gallon and then the bars drop off really fast...and from what i can tell, theres about a gallon left when the red bar starts blinking. Especially if you turn the bike on while its on the kick stand and not straight up
SO!! One gallon for the first bar, one gallon for the last bar, and a little under two gallons as the lions share of the gauge. I guess that makes sense