Guys I think I have a faulty speedo sensor. I have pulled the instrument panel apart and checked as much as I can there following intructions from this forum, Thanks. I am pretty sure the sensor is faulty. Can anyone help.

GPG

have you done the usuall ....

pull the sensor ...and clean it up (usually gathers crap around the centre pole )

get to the under rhs side cover and deoxit the join in the cables

first things to try

Hello mate
I've had a few problems with this before, most of which turned out to be the connector behind the right hand side panel. Follow the wire from the final drive end to where it connects to a flat 2 prong connector. Clean it thoroughly with an electrical cleaning agent of your choice (DeoxIt), then attach the wire to the frame with a cable tie. Mine kept jiggling loose.
If you still can't find the problem, undo the single screw at the final drive connection, and
gently pull the sensor out.(I have had to use a thin flat blade screw driver underneath it
to pry it up a bit), It just fits in the hole as there is a rubber bung around the end.

Apparently if you hold a heated soldering iron close to the end of the sensor, it will make
the speedo needle move as in motion.

If that fails, send me a pm as I have a spare used one here that I know works.
Good luck
RT Sorry Charlie was too busy typing to see your reply.

If you have a laptop, get the Karamba software and test your speedo from the laptop.
Check this post.

Thanks guys I will try all the above.

With a 50Hz power supply you should read 60.9kph. You may need to take the sensor out of the drive unit as some soldering irons don't have a strong enough magnetic field.

The advantage of using a mains soldering iron is the magnetic field will test the system end to end the iron does not need to be hot and if it is the type with a thermostat in it cold is better since when it is not heating the field will be very small.
Regards,
K-BIKE

Apologies for reviving this old thread, but could someone clarify, if the soldering iron makes the speedometer and odo/trip work properly, yet they don't work when ridden with the sensor installed,,,,is the sensor bad or good? Does it mean theres a weak or corroded connection somewhere? And is it normal for the sensor to get oil on the bottom of it when mounted/working? thanks all

wheezy

if things are connected properly ....then yes the soldering iron will emulate the rear wheel turning to the rest of the electronics

along the path to the speedo is a few joins ...one on the right hand side (behind the side cover  two pin flat type connector , similar to the brake light switches ) and another when the loom joins the instruments in that big two connector which has 2 parts .

we have found that the connectors corrode to a degree , over time , cant be helped in the atmosphere we subject bikes to  rain, sun and age and dc voltages .

look up "deoxit" ...found throughout the forum as a recommended and proven electrical connector cleaner for such issues

and yes the sensor is inside the rear drive housing subjected to the oil within .

we also find that small grains of metal wear off the gearsets within the dif (for want of a better word ) do collect around the sensor (basically shorting it out magnetically , with little bridges of metal between the central pole  and outer ) you may want to clean these off for proper operation  to start with . wd40 etc and a clean rag might do this well .

just a heads up


good luck

I'm pretty familiar with the connections already, and have cleaned them along the way to repairing the gears in the speedo itself. My bike is very corrosion free, btw, due the very dry climate here.  I'm trying to determine if the sensor is bad or not as I'm pretty lost with electrical diagnosis. Basically, if the soldering iron works, does that mean the sensor is good and the power of the iron overcomes any poor connections?  Was actually hoping the sensor is bad, because I've had the speedo apart a dozen times or more cleaning and repairing.

you might try measuring the sensor with a multimeter  from the connector behind the side cover ....your looking for a few ohms (range 0- 2000 ohms )

then take it a stage further and try the same measurement at the instruments connector .

if you see any variation you are on the right path to finding the problem

alternatively you could use the multi meter on ac volts  and measure the connector at the side cover , rear wheel turning ( maybe in first gear idling )

you should get just under 100 millivolts  that's 0.100 volts ...if your multi meter goes on low voltages  ...try the 2 volt range if its not an autoranging meter

if all these test pass ...then it could be earthing to the instruments ...the electronic inside the instruments etc ....

what I do is try to prove a thing to be good ...along the path

diagnosis isn't hard ....if you eliminate the likely issues

problem is, folks discount issues without proving them to be good ..or bad..it takes time, patience and some little knowledge to know what to look for, if its a foreign concept .

its totally logical ....pretty hard in a new to you thing

I believe the self-cancelling indicators are dependent upon the speedo sensor to measure the distance traveled with the indicator working. Therefore, if your indicators self-cancel after 300m (?) you may assume that the sensor is functioning and your problem is elsewhere. The converse is probably true, but based on the principle of "the grass is wet, therefore it is raining", not necessarily so!

true indeed mr grumpy

if the signal is passing though the electronic board properly

it would clearly indicate the meter motor is not working correctly ...but we have seen that the film circuit board has been known to have issues in the past ...sometimes requiring a rewire of the joining circuitry 

but a good identifier you have suggested

cheers !

I found the answer, I think, and that is the soldering iron technique can simply confirm (or not) that all of the electrical connections are good.  This also caused the signals to shut off, but speedo was working also so I can't say if one would work and not the other.  What seemed to be the cure was when I took a small needlenose pliers and rotated the little metal stub on the bottom of the sensor. Maybe there was a bad connection in there, but now everything works as it should. My trip meter numbers are turning a little notchy so far but I can live with that. Very glad I found out on this forum never to reset the trip while moving, as it can damage the gears in speedo. Thanks again for the input guys!

What model bike is it Weezy. I ask because the early Ks had a different sensor, it can be identified by the phillips head screw in the top of the sensor and can be pulled apart, the later is a sealed unit and can only be opened with considerable force like a hammer.  I think they were different in the resistance as well.
You could have an early type and rotating the centre has reconnected some wires. Likely to be temporary but keep the fingers crossed I've had fixes like that keep working for years.

These instructions on how to calibrate your peedo may be helpful.
http://classickbikes.com/ckb.tech/0.ckb.tech.files/speedocal/speedocal.htm

Also if you need a wiring schematics diagram, print this out A3 size.
http://l.bitcasa.com/Z2z4z-IW

Cheers

RicK G wrote:What model bike is it Weezy. I ask because the early Ks had a different sensor, it can be identified by the phillips head screw in the top of the sensor and can be pulled apart, the later is a sealed unit and can only be opened with considerable force like a hammer.  I think they were different in the resistance as well.
You could have an early type and rotating the centre has reconnected some wires. Likely to be temporary but keep the fingers crossed I've had fixes like that keep working for years.

My bike is an 85 K100RS, and it does have the old style sensor apparently, because it has the phillips screw holding it together, which I removed and took the sensor apart but saw nothing really that looked wrong with it.  Still working after 200 miles so I'm hopeful.

Kaptain Holister wrote:Also if you need a wiring schematics diagram, print this out A3 size.
http://l.bitcasa.com/Z2z4z-IW

Cheers

Hmmm. Interesting how this work migrated from the forum to many other sites.

The same schematic as well as other colour ones is available on the forum download page 

CF

indeed bert ....

your reference diagram is great ...
cheers

Crazy Frog wrote:

Kaptain Holister wrote:Also if you need a wiring schematics diagram, print this out A3 size.
http://l.bitcasa.com/Z2z4z-IW

Cheers

Hmmm. Interesting how this work migrated from the forum to many other sites.

The same schematic as well as other colour ones is available on the forum download page 

CF

Well that's probably where I found that. That link is not to a site but to my own personal files. I have resized the PDF so that it prints out properly to a full A3 page. Its hard to follow those schematics at the best of times without it being so small.

Cheers