Speedo rotor replacement

Problem: K3 naked digital speedo just started reading all over the place like a random number generator. Sometimes also worked fine, and also sometimes just 0.

So I took the the front wheel off and saw that the speedo rotor was mangled. bought a new one for £17.54 quid and here is me fitting it on:



Old rotor:


New on left, old on right:


Bit where it fits in:




So I swapped them over, and screwed it all back together.

Result: STILL BROKEN

Even when sitting still it sometimes reads all over the place. So my guess is that it is an electrical gremlin. The old rotor might still well have been functioning! Anyway, it clearly needed replacing anyway. I hope this helps some of you who are also having problems right now. I will update further once I have poked the electrics a bit.

[Sid Squid]

Are you sure you haven't broken the new one when fitting? They are pretty fragile and it isn't unusual to hear of non functioning speedos after the wheel has been off.
Even with broken drive lugs you can still turn it quick enough by hand to get a reading of 1 or 2 mph, try that and see if the problem is still there before checking further.
The other sometimes troublesome area is the cable getting trapped between the lock stop and the frame, damage from getting squashed there isn't always immediately obvious.

Originally Posted by Warthog

So I took the the front wheel off and saw that the speedo rotor was mangled. bought a new one for ?17.54 quid and here is me fitting it on:

Looks like Phil fitting it to me.

Looks really thoughtful doesn't he?

Well at least it wasn't 18 quid wasted although I suppose a whole replacement sender with cable to the loom would have discounted any pinched problem as suggested by SS.

Good luck Nick.

Originally Posted by Sid Squid

Are you sure you haven't broken the new one when fitting? They are pretty fragile and it isn't unusual to hear of non functioning speedos after the wheel has been off.
Even with broken drive lugs you can still turn it quick enough by hand to get a reading of 1 or 2 mph, try that and see if the problem is still there before checking further.
The other sometimes troublesome area is the cable getting trapped between the lock stop and the frame, damage from getting squashed there isn't always immediately obvious.

I was fully aware of people breaking it when fitting a new one so I was constantly shouting at Phil to make sure he lined it up properly! I think the clue here is that after we had replaced it, when sat still, it was still reading all over the place. Surely a squashed rotor can't give a false positive reading when idle? Must be electrical. I shall check the rest of the wiring for squashedness, cheers!

Ah man - WARTHOG - I was looking to you before embarking on my journey of speedo rotor discovery. Mine never did random numbers but now doesn't leave 0 ever. Clock, temp and rev counter all perfect.

Originally Posted by krhall

Ah man - WARTHOG - I was looking to you before embarking on my journey of speedo rotor discovery. Mine never did random numbers but now doesn't leave 0 ever. Clock, temp and rev counter all perfect.

Well that does sound like a broken rotor.

[Stu]

Originally Posted by Sid Squid

Even with broken drive lugs you can still turn it quick enough by hand to get a reading of 1 or 2 mph, try that and see if the problem is still there before checking further..

So are the 4 flanges just lugs that aid in the turning? & it is the turning that records the speedo? so not like my system that requires 4 magnets to pass a sensor?

Nick, I still have 2 speedo rotors/sensor's/cables if you want to try them.

I'am going through the same thing at the moment.

Someone swapped my speedo for a random number generator.

Had the front wheel off and the rotor out last night, rotor was fine.

Put it all back togther, tunet the power on and, back to random numbers. - pooh

Next step was to free the cable and inspect it for damage. - none obvious - pooh

Next disconnect the plug under the tank, spray it all with ACF50, no WD40 to hand.
Put it back togther - nice steady zero reading.
Take it for a run - nice steady zero reading - pooh.
Then the random numbers start again - POOH POOH.

Now I'am stumpped, any advice - please!














Pooh poohing my pooh poohs would be unkind.

I'm trying the speedo rotor replacement tomorrow, if the weather is kind to me!!!

Originally Posted by seedy100

I'am going through the same thing at the moment.

Someone swapped my speedo for a random number generator.

Had the front wheel off and the rotor out last night, rotor was fine.

Put it all back togther, tunet the power on and, back to random numbers. - pooh

Next step was to free the cable and inspect it for damage. - none obvious - pooh

Next disconnect the plug under the tank, spray it all with ACF50, no WD40 to hand.
Put it back togther - nice steady zero reading.
Take it for a run - nice steady zero reading - pooh.
Then the random numbers start again - POOH POOH.

Now I'am stumpped, any advice - please!














Pooh poohing my pooh poohs would be unkind.

I knew a general who was pooh poohed once. In the end they had to disband the regiment!