'12 600 144"

Why would the fuel economy drop off so badly? January got 11-13mpg, 10mpg all last month and low of 9! 8.5mpg yesterdays ride, all in similar conditions. Temp don't matter, cfi. Starts up and runs pretty darn good for a 600. But my old carbed '08 600 144" got 12+mpg in any snow condition. Making me miss that old bag, finally sold it after more than 7 years of owning it.
Reeds? ECU going nuts? once saw a low voltage level, turned off and back on and ran great(so to speak)
Help me figure possiblities, thanks.

Enough snow in our area, less than ideal but more than last year. Pulled pipe sensor and cleaned it up. Changed belt, 1200 miles on 1115 belt and has missing piece on inside, wtf? Never made noise or anything as this thing still seems like it runs since I bought it. Regardless I put on s brand new 1122, try that for grip. Going try change out my weights, original getting a lil bit worn, 4932 miles on it, 2525 when I bought it last May.
Baffled. This thing pull hard, rides effortlessly.
Increased oiler link too. Not throwing sensor codes, nothing. Idles as should. Hasn't killed a plug in a month.