20 mph speedo error???

[WhatYes_imp]

Been in discussion with the seller of a 2013 model and he says the only thing "wrong" with the bike is the speedo is off by 20 mph; it reads 80 when you're doing 60.

Now I've owned plenty of bikes with as much as a 10% variation. My current '08 GSX650f reads 70 when you're going about 63, but man.... 20mph???

He didn't mention whether the gearing had been changed from stock. If it's not that, it concerns me. Your thoughts?

[pdedse]

Been in discussion with the seller of a 2013 model and he says the only thing "wrong" with the bike is the speedo is off by 20 mph; it reads 80 when you're doing 60.

Now I've owned plenty of bikes with as much as a 10% variation. My current '08 GSX650f reads 70 when you're going about 63, but man.... 20mph???

He didn't mention whether the gearing had been changed from stock. If it's not that, it concerns me. Your thoughts?

The CB1100 are pretty much spot-on with speedo. Others will chime in as to reasons why this one isn't.

[pekingduck]

Been in discussion with the seller of a 2013 model and he says the only thing "wrong" with the bike is the speedo is off by 20 mph; it reads 80 when you're doing 60.

Now I've owned plenty of bikes with as much as a 10% variation. My current '08 GSX650f reads 70 when you're going about 63, but man.... 20mph???

He didn't mention whether the gearing had been changed from stock. If it's not that, it concerns me. Your thoughts?

CB1100s have an electronic speedo with a speed sensor on the rear wheel, so gearing doesn't affect the speed. Unless he's doing a burnout.

[max]

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 ?

[Ayrshire Dunx_imp]

Could the electronics be flashed with a more up-to-date version? The new style speedo has a lower top speed for the same arc. This is me guessing!

[max]

Here is the inside of the instrument cluster under repair;
https://www.youtube.com/watch?v=aEMKcnTuzMY





If you can help us find the new software and show us how to load it into the micro that would be great Ayrshire, I've not been able to do this before but am very willing to learn this stuff, sounds good, thanks for the offer .

[Lord Popgun]

My first thought turned out to be what Max said. The ring has to be flat, all the slots not bent or anything and the sensor tight and spaced from the ring according to the gap spec.

[Sparky80_imp]

part in question is about $70 according to Partzilla. called a pulser ring https://www.partzilla.com/product/honda/...3e7918b0d7

[WhatYes_imp]

Great info here, folks and exceedingly helpful. I am moderately mechanically inclined; do my own oil changes, have removed wheels from bikes to get new tires, etc. If it IS the pulser ring, how easy/tough of a replacement is it?

[pekingduck]

WhatYes,
I am assuming this is a bike that you are considering from a distance about buying.
Max's question of the 20mph variance is a good one. So, questions we would have to help you solve the problem if possible.

- Is it a constant 20mph off, or is proportional to actual road speed?
- Is the odometer reading correctly?
- At 60mph, when it is indicating 80, what is the tach reading? You can check this while on the centerstand.
- Original owner?
- Did the problem occur suddenly or gradually?
- Any accidents?
- Any modifications? For all we know, it may be an aftermarket speedo.