SV650S-K3 Speedo failed (random numbers) - Rotor seems OK, speedo drive problem?

[Tallguy]

I've read a few posts about speedo issues, indeed my rotor has failed once before and was replaced.

I had new tyres fitted a few weeks back and the speedo issue happened, I figured it was the rotor damaged by the fitter, same as last time.

However, my mechanic (Alan Lear of Winchester) stripped it down and he says the rotor looks like new, so he cleaned it all and put it back together again.

It seemed to work for a while (days) but now it's back to occasionally-correct but mostly-random numbers. It seems to be worse in hot/harder riding.

Alan Lear says that it's more likely the speedo drive than the rotor, based on his assessment of it last week.

Can anyone provide some info about this? E.g. if I searched on The Bay of E, could I look for speedo drives for SV650 K3 onwards or would only certain ones work? Would (say) GSX or other speedo drives work? Can the existing rotor look OK but actually have failed invisibly? Or could it be something else of which I'm ignorant?

Thank you, o mighty Org, I supplicate myself at your (cheesy) feet.

[punkyp]

I had this problem. Lifted tank and took out the airbox and found the connector for the speedo (use service manual) made sure contacts were clean and sprayed some WD40 for good measure, re-assembled and not had the problem since.

[Tallguy]

I'll have a look and let you know, cheers PunkyP!

[Runako]

(Thread segway) Fooking Thunder Road garage ... ****ed me right off! Have the same problem as you guys and checked rotor, no damage etc. My 16k service came around so asked them to have a look or recommend what could be causing the fault. "No problem" I was told. Of course, they don't know that I've read a lot on the subject on here. I wanted them to make their own assessment.

I pick up the bike. "Oh you need a new speedo drive. That's £120". Ok, what did you find? "Oh well its something to do with the wiring (then proceeds to badly sketch a squiggly line with a circle at one end and a box at the other) ... you see, somewhere in here is the problem". So what is the problem exactly? "The wire running from the wheel and in the frame is a sealed unit so its somehwere in there but we would have to pull it apart to tell".

So you don't know what wrong? "Well, its a common problem with these see. Once it goes you just have to buy the new part". But I've heard a wire could be corroded or it could be a loose connection. Could it be something like this? "Well there's no point opening it up to look as you'll have to change the part anyway".

Why must garages be such tits? I would much rather him say, "We weren't able to isolate the reason for the fault from a visual inspection so you'll have to check the loom or under the tank to inspect the connection ... you may need a new speedo drive or it could be something simple to rectify like a loose connection". Fair enough.

But £120 for a new part and trying to blind me with ignorance when you haven't even cheecked? So, I'll being doing the checks you recommended Punkyp and lets see if the 'simple' solution works. Cheers.

[Tallguy]

Disconnected the speedo drive cable, it looked good and clean, but I scraped the three pins with a tiny sharp screwdriver and put a drop of ACF50 in each pin holder, reconnected and put the airbox back on, dropped the tank.
So far, it's worked - I'll reserve judgement til I've had a harder ride, but so far so good!

For the sake of half an hour and some dirty fingers, give it a go!