I was riding home and the speedo and odometer failed.
Does it have a fuse or is it smoothing else that is simple?

It could be something as simple as the connector from  the speed sensor which is located near the rear drive.  Follow the cable from the speed sensor up to the connector. Try unplugging it and then plug it back to see if that fixes your problem.  It's work for me before.  Especially after a rain.

The sensor where I goes into the final drive can also get dirty. It needs to be removed and cleaned. Bricks are known for electrical bugs which can be cured easily by going over all the connectors with Deoxit.
Regards Martin.

Has anyone tried the WD40 contact cleaner? Deoxit is about 5 times the price as the WD here in the UK so just wondered as WD40 products are normally pretty reliable.

The WD40 Contact Cleaner, cleans away the dirt, grime or whatever, leaving a surface that is not protected.


The DeoxIT (note the correct spelling ) cleans and covers the surface with a protective barrier and it enhances electrical conductivity. Top stuff and worth the money in my humble opinion.

Cheers BlaKey, I'll have to ask Santa if I've been a good boy this year and add it to my Christmas list, although I may also need to ask for a dictionary as my spelling has never been good!

@Stumpy wrote:I was riding home and the speedo and odometer failed.
Does it have a fuse or is it smoothing else that is simple?

A sudden failure (rather than failing after a period of being erratic) is likely to be the fuse. I lost all instrumentation while riding (a while back) and I seem to recall that it was the tail light bulb blowing which took out fuse no.1. 

Use a test meter to electrically test all your fuses - they do get tired and can fail without any overload reason. Who knows, you may still have original fuses fitted!

Instrument cluster power comes from fuse #1.  If that fuse blew, it would also disable power to front and rear brake switches, clutch switch, heated grips, and additional instruments.  You'd probably notice a lot more than lack of speedo and odometer.  You'd not be able to start the bike, you'd have no brake lights and instrument lights would be gone as well. Since you haven't mentioned these symptoms, have to assume fuse #1 is intact.

Most likely it is the connection to the speed sensor in the rear drive.  Either the connector under the right battery cover is corroded, or the 24-pin cluster connector is corroded.  Disassemble, clean and re-seat several times to ensure contact is good.  It's unlikely to be a bad speed sensor, but you could also remove and clean it as well.

Download K-diag and test your speedometer if these instructions fail.  K-diag is available in the download section. Usage instructions here.

I took the sensor out and wiped it clean, I then checked the connector for corrosion.
When I put the bike in gear the speedo started to move up and register.
Hopefully this is fixed, I have looked at the wiring and it looks knackered, I may see if I can get a new loom made.

Post 9 here:

https://www.k100-forum.com/t10428-comberjohn-s-ghost

It might make your life a bit easier if making a new loom.

@Dai wrote:Post 9 here:

https://www.k100-forum.com/t10428-comberjohn-s-ghost

It might make your life a bit easier if making a new loom.

Thanks for that, It is just what I need.