Speedo reading again, only different

[Toooldtodie]

It was a pre-abused bike. Does a K4 or earlier sender unit fit on a K5? That could be the root cause if that is the case... clutching... ooh there's a straw!

[Bibio]

k4 do not fit k5

[Toooldtodie]

Sweet! One thing ruled out.
Voltages, current and resistance next then.

[Bibio]

what i meant by that was that both speedo drives are exactly the same but the internal rotor are different (the thing with the 4 lugs). if you fit a later inner rotor to an early outer you will read double the speed. they both look exactly the same. same goes for whole early/later units. yes K4-5 bikes are a nightmare for this.

was the bike reading the correct speed before you changed the inner rotor?

[Bibio]

Magnets (inner rotor) part #
early K3-4 34983-21E00 (4 pulse)
Later K5> 34983-27G00 (8 pulse)

the confusing part is K5 bikes that are actually late registered K4

[Toooldtodie]

Thanks for your help with this. It's def K5 as its got a black frame.
Before the rotor was replaced it was reading under by 20mph or so ie. 42mph indicated at 60. Now it reads 20mph over at 30 and 30mph or so at 60.
Voltage and current to sensor are 10.4V and 90mA. But did not get any current reading when powering sensor direct from battery. I suppose that points to the sensor being faulty, but weird symptoms? I couldn't test voltage generated by sensor as I can't get front wheel off the ground.
If it was reading exactly double I'd be chuffed as I'd have an answer.

[Bibio]

the K4 had a black frame as well.

ok i cant go any further due to you saying that you cant get the front wheel off the ground so to me this is saying that you have not visually checked the inner rotor/magnet. there is no way you can check the drive if you cant get the wheel off the ground as you need to rotate it to check it and count the pulses.

the first check that should be done is visually check the inner magnet/rotor on the speedo drive. if you dont do this then you are pizzing against the wind trying to do anything else.

was the speed ok after the new magnet/rotor was fitted?

broken magnets usually read under, bounce all over the place or stop working.

not the correct part will show double or near double the speed all the time.

with you saying that its reading double or near double then i would say that you have the wrong part.

what did you connect to your 12v battery?

[Toooldtodie]

Got new tyres and rotor fitted 2 weeks ago. Was reading under before, now over since new rotor. I will get them to replace rotor with 4 pulse and see what happens... who knows what was thrown on the bike from the parts bin at the factory?
Thanks for your considerable help Bibio.

[Toooldtodie]

Originally Posted by Bibio

what did you connect to your 12v battery?

I went through these checks:

https://www.youtube.com/watch?v=H7d9fukFccY

Got no current from third check in the video for current despite getting a voltage reading with same set up.

[Bibio]

current will only pass as it pulses and its these pulses that you need to count.

if your saying that it was reading double or near from when you had the inner replaced then i would bet top $ its the wrong part.