Speedo Sensor Needed

[Timbollew]

So I'm riding in too work this morning and my speedo is basically bouncing all around the place. Seems to be reacting to my revs more than my speed, shooting up to 140mph (I wish) then back down just all over the place. After the engine warmed up it seemed to get a little better but still not right. I'm guessing that I've probably got a dodgy connection somewhere, anybody else had this happen?
Going to whip the tank off this weekend and check the connections until then I'll just freestyle it.

[Deefer666]

either the drive dog has broken up in the speedo drive or the wire has been caught by the front disc and damaged, my money would be on the drive dog.

[Kentish]

What's a drive dog?

[HarryHornby]

[Deefer666]

inside your speedo drive is a ceramic collar with two magnets on it, this is a drive dog. They break up and then you get really weird speedo readings. Pull the front wheel off and have a look

[Wookee]

The original part was apparently very brittle and the lugs break off easily when you take the wheel off. There is a newer part, pictured below, that you will probably need. There is a bodge to it if you still have all the bits you can just superglue them back together. Mine is currently bodged and I have this part ready for when it breaks again.

[Deefer666]

That, is a drive dog!

[Punkstig]

Funny, I'd assume it was the wire worn through and grounding against the fork leg or similar!

[Deefer666]

If you read my original post that was my 2nd guess 

[Timbollew]

I'm gonna have a look today. I've replaced the drive dog before with the newer part, there is a funny noise coming from the front wheel though so we shall see.

[Andy FZS]

Funny noise from the front wheel is a classic symptom of your drive dog....barking . No it is honest.

[wickedmonkey]

Mine went crazy for a couple of days and then back to normal and has been for months now.


There was a post about a month ago from someone who had the same symptoms as you describe. Can't find the post though.

[Fazerider]

Mine had the same symptoms when I routed the cable the wrong side of the brake caliper. The cable got close enough to the disc to get hit by the head of each disc bolt... once that had worn through the insulation the speedo reading went all over the place.
I bunged a bit of heatshrink sleeving over the damaged bit, routed it up the outside of the caliper and it's been OK since.

[Andy FZS]

http://foc-u.co.uk/index.php?topic=8649.0
Is this the one? I hope I've added the link and not made a foc of it.....

[wickedmonkey]

No, just found it: http://foc-u.co.uk/index.php/topic,11710...#msg127441

[Timbollew]

I've still not had a chance to take a look at it, but there's been a development. This morning on the way to work same thing speedo jumping around crazy. I switched of my headlight and the speedo returned to normal, I then stopped at some lights and thought lets try some other stuff, If I have the brake light on all ok but brake light on and indicator on it bounces up and down in sync with the flash.
Surely this means it's not the drive dog? Gonna have to have some investigative work this weekend, but I hate electronics  :'(

[Punkstig]

Grounded wire, see above!

[Timbollew]

So I've had a look tonight. I'm 90% sure it's not the drive dog as I'm having problems just on idle without the wheel moving.

Checked the wire from speed sensor, it's not grounded no breaks or anything looks perfect. Checked all the connections in the little box under the tank and all seem fine. Disconnected them and reconnected to make sure all was ok.

I've got a feeling it's going to be my speed sensor. Anyone have any thoughts? From what I've seen these are fairly expensive. Anyone here breaking an fzs with a working speed sensor

[Timbollew]

Anybody have a speedo sensor for sale? I'm pretty sure this is my faulty part. As I found something on another forum that sounded like my problem that was resolved with a new speedo sensor.

If you've got one or know of one please let me know, dealer price is around £130!

[Dead Eye]

I had to replace mine a few years ago and ended up finding someone breaking a 600 and getting them to send me the unit. Ended up costing £25 inc p&p - I'd recommend this route as buying new is insanely expensive as you have found out