11-29-2021, 05:41 PM
First thing i would look for is the " tone ring " , it is the perforated black disk inside the rear brake disk.
Put the bike on the center stand and look carefully for any undulations in the disk by slowly rotating the wheel.
This ring interacts with a sensor which is mounted just below the brake caliper rear sliding bolt.
The ring should be flat and not bent in any way, it runs very close to the tone ring and any wobble could send the wrong
info to the speedometer in your case, have a look if the sensor or the bolt is not loose.
Normally and in the case of an abs model this sensor compares the front and rear wheel speed and reacts when the brake is applied to retain traction to the wheels and also transfers the rear wheel signal to the speedometer.
If you were to listen to the signal you would hear a tone which changes with the wheel speed hence the name tone wheel.
Does the speedo always indicate 20 mph difference or does it change and is a percentage of the speed i.e. 40 mph at 30 mph ?
Put the bike on the center stand and look carefully for any undulations in the disk by slowly rotating the wheel.
This ring interacts with a sensor which is mounted just below the brake caliper rear sliding bolt.
The ring should be flat and not bent in any way, it runs very close to the tone ring and any wobble could send the wrong
info to the speedometer in your case, have a look if the sensor or the bolt is not loose.
Normally and in the case of an abs model this sensor compares the front and rear wheel speed and reacts when the brake is applied to retain traction to the wheels and also transfers the rear wheel signal to the speedometer.
If you were to listen to the signal you would hear a tone which changes with the wheel speed hence the name tone wheel.
Does the speedo always indicate 20 mph difference or does it change and is a percentage of the speed i.e. 40 mph at 30 mph ?