Average MPG's dropping and other things

[Hayabusawannabe]

Lately I've notice my MPG's are dropping, I used to average about 45 mpg and about 215 mi per tank. Now after several years I'm down to 40 mpg and about 150 mi. Does she need a tune up? Keep in mind this is my first bike so I dunno, I forgot to ask my mechanic the last time I had tires put on.

 

[dadofthree]

How many miles and have you ever changed plugs ?

Alcohol reduces mileage and the % of alcohol added to gas has been creeping up. So if you went from 100% gas to 15% alcohol during this time it could explain this.

 

[GIXERHP]

Also what is the time period that the change has happened over?

 

[Hayabusawannabe]

I don't think he changed the plugs when he synced the throttle bodies about a year ago. As for alcohol don't know how much is in the gas either, I'll have to look into that. Started dropping about 8 months to a year or so ago, I got lazy and stopped logging the mileage on fuelly.com and just started looking at the MPG gauge. If I go about 5 - 10 MPH slower than usual it goes up but that's no fun!

 

[dadofthree]

This bike has a sweet spot at 4K RPMs. If you vary much from that you'll notice a two to three MPG drop. So many variables on fuel mileage. Also from memory when I would change the plugs on the gen I I would notice a drop in mileage for a few thousand miles.