Speedometer bounces up and down and gas mileage is HORRIFIC

hey guys, my speedometer jumps up and down and when i pull the clutch it goes to zero.. not only that my MPG is horrible.. i had the 4th Gen VFR for about two months and this is by far the worst mpg Ive gotten. I use to get about 135 miles a tank now I get about 80.. changed the chain and sprockets, new fuel filter, air filter, and oil...

any idea whats wrong? could be it be my R/R? how do I know if it has been replaced since the stock one? thanks guys.

 

I doubt your R/R would give you crappy fuel mileage like that, buy I can't tell you for sure. I'd also take a look at your brakes, because if they're dragging, they could also cause crappy mileage as well. I had the same issue on my VFR and changed the chain, sprockets, as well as the complete brake system, and my mileage went back up. To this day I'm notsure what fixed it, but it's definitely better now. Also take a look at your spark plugs, as they'll give you a clue on whether you're running rich, lean or just right. Too much fuel going through will give poor mileage as well. When my R/R was going bad, the speedo would also bounce around , but I also had the same thing happen when my negative terminal on my battery came undone. There's a test that you can do to see if the R/R is bad, but I can't remember what it is, sorry...

 

still no luck...

Thanks Douglas, this gave me some good insight into what to look for. So I put the bike on the center stand and sounds like my my back brakes are rubbing against the rotors. that might be the reason the shitty mpg. I checked hte battery terminals and they are connected fine. I doubt its my R/R because all of my gauges work fine, including the clock other than the speedometer. I removed the speed sensor and took a pic, (attached) Anyway of telling if it's shot? i noticed that my odometer is not working properly, if i ride 20 miles it would log 4-5 miles. does this have to do with the speed sensor as well?

 

From what I've seen, the speed sensor socket (white plastic) will break, causing your milage indications to go out of whack. Yours looks fine, although obviously something is waaaay wrong if you're getting the type of indication that you mentioned. Gearing changes can affect indications, but can easily be fixed with a Speedo Healer. I would check all the connections from your speed sensor to your gauges, to ensure that there isn't any corrosion, and that all the connections are secure. This will help rule out those as possible issues. I rwally don't know what to tell you other than that for now, as a non-functional odometer is kinda new to me.