get in there and clean the air filter..
my '86 with a clean filter, fresh correct valve adjust, carb synch, and idle adjusted at 1100 rpm netted me almkst 50 mpg for about 6 months, and when it started droppin, claning my k&n, and oiling it properly brought it back to 48+ mpg..
but then that was a silverdammit bike.. with 100k miles on it... (138,000 when I sold it) .
I have regular unleaded available here. Typically I get 40 to 43 miles per gallon. I will fill up this next week and find out what my mileage was for today's ride. I have 240+ miles on this tank full and still did not switch it to reserve.Rode it to work today. Total of 259 miles, still not on reserve. Filled it up with 5.798 gallons of regular unleaded for an average of 44.67 mpg.