Speedometer too SLOW by more than 10%

[snapple]

Most speedo are off by a few %, but they usually show a higher speed than GPS.  I just bought a used '17 FZ07 and on a 200 mile ride back home, I checked with my wife's car and GPS and confirmed that my speedometer is more than  10% slower (63mph vs 70mph).  This also affects the odometer (e.g. trip meter 71.5 miles vs 80 miles), so the bike I bought with 8.7k miles is actually closer to 10k miles

The ABS light also never turned off, so perhaps this is related. I noticed that the rear ABS sensor is very close to the toner ring, but the front sensor is about 0.8cm away from the toner ring.  How close is it supposed to be?  I have no idea how to adjust the sensor location, the extent of my repair experience is oil changes and bolt ons...

Any help would be appreciated.  

 

[Paulb5950]

On 9/4/2023 at 7:50 PM, snapple said:

Most speedo are off by a few %, but they usually show a higher speed than GPS.  I just bought a used '17 FZ07 and on a 200 mile ride back home, I checked with my wife's car and GPS and confirmed that my speedometer is more than  10% slower (63mph vs 70mph).  This also affects the odometer (e.g. trip meter 71.5 miles vs 80 miles), so the bike I bought with 8.7k miles is actually closer to 10k miles

The ABS light also never turned off, so perhaps this is related. I noticed that the rear ABS sensor is very close to the toner ring, but the front sensor is about 0.8cm away from the toner ring.  How close is it supposed to be?  I have no idea how to adjust the sensor location, the extent of my repair experience is oil changes and bolt ons...

Any help would be appreciated.  

 

Not sure if you had seen the previous reply, but did happen to check the fuses?

Lots of people remove the ABS modules fuse so they can Hoon around a bit easier. Fuse box is under the passenger seat. 

Check to see if the fuse has been removed or is possible blown.

 

As for the ABS and speedo being linked I don't believe that the two are linked in any way. The speedo sensoyon these bikes is not located on the wheel, so it's quite possible one of the previous owners changed the gearing.

[AP996]

9 hours ago, Paulb5950 said:

As for the ABS and speedo being linked I don't believe that the two are linked in any way. The speedo sensoyon these bikes is not located on the wheel, so it's quite possible one of the previous owners changed the gearing.

On ABS equipped bikes the speedo uses the ABS wheel sensors for its input. On non ABS bikes the sensor is on the gearbox.

[Paulb5950]

22 minutes ago, AP996 said:

On ABS equipped bikes the speedo uses the ABS wheel sensors for its input. On non ABS bikes the sensor is on the gearbox.

Interesting, I did not know that! Apologies for the wrong info @snapple

[snapple]

58 minutes ago, AP996 said:

On ABS equipped bikes the speedo uses the ABS wheel sensors for its input. On non ABS bikes the sensor is on the gearbox.

This was my understanding as well, which is why I'm confused about the speedo being so off. The sprocket shouldn't have an effect on wheel speed, right? 

[Paulb5950]

2 hours ago, snapple said:

This was my understanding as well, which is why I'm confused about the speedo being so off. The sprocket shouldn't have an effect on wheel speed, right? 

Yeah if the pickup is off the wheel then gearing wouldn't matter.

[mjh937]

Do you have stock sized tires?   I do not know if that would make that much of a difference but it is the only thing I can think of.