Posted this in an older thread - not sure if anyone saw it.. There's been HUGE fluctuations in people's MPG reports - I'm guessing it's because of the very inaccurate speedo/ODO.

I have a real # MPG report.

I use a GPS whenever I drive - it has a trip odometer on it that I can keep track of tank miles. The stock speedo/ODO is off!

The bike: 2007, FMF jet kit - 128 main, FMF needle, stock pilot, 2.5 turns out. FMF powerbomb header, Q4 muffler, air box lid removed, UNI air filter, carb stuff removed.

I filled up at the local Texaco which is the only gas station for miles that has seperate pump lines for each octane rating.. So, I filled up with 93, just under the rim.

Drove to work a couple times - 35-55mph, 12 mile commute. Also used it for some town spirited driving

It sputtered a bit at 78.2 miles on the GPS ODO. At 78.5 it died and I switched to reserve.

I got to the gas station at 80.8 miles.

Filled up using the exact pump at the start of the test, and filled to the same line - put in 1.539gl of fuel.

Do the math and get a 52.5 MPG tank. Going further with the math - the stock tank is 2gl, that means reserve is just about .5gl, = about 26 miles before you run out of reserve.

I'm sure I can get 60mpg + out of it if I drive it like a sane person

Someone needs to do this exact test with a stock one The stock speedo is way off!

 

so what did the tripometer say compared to the tripometer on the bike? How far is it off? Good info man.

 

I knew that Q would come up! I messed up and never reset the bike's trip ODO at the same time.. I will definitely do that next fillup though.

 

I noticed that on my street bike on my ride on sunday, me and my buddy would fill up and then both reset the trips.... and the next time we stopped they were 1-2 miles different... lol

 

Yup, the same thing happens when my girlfriend and I ride together. My KLX's odometer will say one mileage, while her XT225 will be 2 to 4 miles more.

I rode past one of those "Your Speed Is" radar signs just a few days ago. My speedo indicated 45 MPH, but the sign said I was only doing 41 MPH.

 

You know Ive heard stuff like this when it comes to cars... you think maybe the factory knows these things are off just for that little bit of DOH safety precautions.. But of course im just blowin out my azz lol

 

Yep I ride with a GPS all the time and my bike with its 13-45 gears and jetting hits reserve right at 80, with hard highway speeds. And the speedometer is off by just over 4 MPH.

 

Only 4mph? At all speeds? Mine's off anywhere between 4 & 9mph depending on the speed..

 

No its off at all speeds. We have some of the speed trap signs that tell you your speed and in a 25 mph zone I can do 29 or 30 and it still reads 25, highway speeds too.

 

I ride with a buddy who's gearing etc is stock.
His odometer reads about 5% more kilometers than my GPS on the same ride.
If my GPS says we did 100K's, his stock odometer will say 105.