speedo off and bad mpg??

91 vfr 750 speedo seems to be off front sprocket is -1 how would i fix this problem and make my speedo accurate? and according to my fuelly so far im only getting 16 mpg??
VFR (Honda VFR750) | Fuelly

 

- on the front or + on the back is going to reduce fuel efficiency, but 16mpg? Is your bike parked in a secure location? I'd be on the lookout for :spy:. Otherwise you might have another problem that without seeing, hearing, or smelling your bike run is definitely beyond my level of expertise. However, don't fret. Someone will be along shortly, who will explain how to get you into countless hours of diagnosing what "maybe" wrong with your bike. Of course, I jest. Good luck.

 

its -1 on the front and no thieves taking my gas

 

Yes, the -1 can affect your speedo. Stock speedo's are off to begin with, so changing the sprockets will only make it worse. You can look into a SpeedoHealer. Probably about $100 to $120.

As for 16mpg - tough to diagnose as JTC mentioned. Need more details.

Hows the temp running?

 

ok but i thought the speedohealer only worked with the newer bikes with digital speedos

and whats the best way to check the temp?

 

I don't know about applicable years for the speedohealer. Was just a thought...

Also wasn't paying attention to the year of your bike. Was thinking more along the lines that if it was running cold, the computer was compensating and adjusting the air/fuel mix, thereby resulting in bad mileage.

Sorry, my posts are useless! lol Was just trying to help.

 

its ok im sure somebody knows what i can do

 

OK I can’t speak with any authority about VFR’s with mechanical speedometers. But harking back to my old ER5/GS500 days here are a few thoughts.

1. Are you sure no one has replaced the speedometer. If they fitted gauges from the wrong model the speedo could be well out.
2. A snapped, but still dragging drive cable could cause a speedometer to under read.
3. Assuming your VFR uses some sort of integral cable drive take-off within the front hub I guess something may have broken inside the hub. (Which may be painfully expensive to get fixed!)
4. Finally are the tyre sizes standard? – The wrong size tire will alter the rolling radius – altering the speedometer reading.

Alternatively : you could buy a SatNav to know your real speed, and if the bike is only doing 16mpg - its time to get a bike shop to check out what is wrong.

Good luck and let us know how you get on.


Skimad4x4 – 6th Gen Militia # 218

 

I'm guessing that you are using the bike's odometer to calculate mileage? If so keep in mind that changing the gearing on the bike will not only affect the speedo readings but it will also affect the odometer readings. This means your mileage shown on the odometer will not be accurate for a given distance travelled. The only true way to calculate your speed and mileage after a gearing change is to use a GPS or calculate your mileage using highway mile markers.

If you determine that your mileage calculations are correct and you are only getting 16 mpg I would guess that the bike has a fuel leak somewhere. Plastic and rubber deteriorates over time and since the bike is 20 years old now there is a good chance some of the components need replacing so check your fuel lines carefully for signs of cracking and/or leaks. If there are no signs of leaking I would next look at your needle jets to determine if they have been replaced with bigger jets at some point which would naturally cause fuel consumption to increase. I really don't think this is the case since bigger jets shouldn't cause that huge of a drop in MPG. Miles per gallon can also suffer if the bike is running rich. You should be able to tell if the bike is running rich by pulling and inspecting your spark plugs. Also check to make sure your brakes aren't dragging and tire pressure is set to the recommended specs.

Rollin

 

i thought this was a no brainer to be honest. If you're calculating the mileage based on the adversely affected odometer your mileage will definetly read low.......you haven't traveled the distance you odometer says you have. The electronic pick up for the speedometer reads at your countershaft sprocket. Changing the size of THAT sprocket will affect your speedo/ odometer. Changing the rear sprocket will not. Go back to a stock front sprocket or get a speedo healer as stated earlier.

 

I thought that changing EITHER sprocket would alter the speedo readout.

 

Bwaaahahahahahah!

 

It is at the counter shaft and it does affect the speedo at either sprocket.

 

another easy way to see if one mile on your speedo is one actual mile is the pesky mile markers on interstate highways. Just try not to weave or change lanes in that mile. They are fairly close. At 60 MPH on your speedo it should take you 1 minute to do that mile.

Way before those fancy GPS things, that's how we had to do it. Not that I'm that old, but was just around before them....

 

this will have no effect on a mechanical Connected to the front wheel hub speedometer