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uncle dick

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I'm currently rebuilding a '99 F650GS and I know it had a history of speedo problems. Could some kind soul start their bike on the centre stand and take it through the gears? Does the speedo work correctly? There are a million answers on the web and I know that the basic speedo signal comes from the rear ABS sensor but wondered if the front sensor also needs to be working to get a proper reading.

Thanks in advance
 
It only uses the rear sensor. Make sure the gap is to spec and the sensor and abs ring are clean.
 
Dansin said:
It only uses the rear sensor. Make sure the gap is to spec and the sensor and abs ring are clean.
Click to expand...

Sensor is new and the gap/ring are perfect. The speedo maxes out at about 10-15 mph. No-one seems to know what sort of signal goes from the ABS to the instruments so I might just have to get a s/h cluster and swap it over.
 
It could be a faulty cluster. May be worth pulling it and checking the connections of the 2 plugs are clean before replacing first.
 
Dansin said:
It could be a faulty cluster. May be worth pulling it and checking the connections of the 2 plugs are clean before replacing first.
Click to expand...

I've had the cluster apart, cleaned the pcb and connectors - no difference. With ign. on, the ABS self test appears ok and the speedo works as described until the ABS warning comes on (presumably 'cos the front wheel ain't moving) and it drops back to zero.
 
So, I got stuck-in a bit further and traced the wire from the ABS controller to pin 3 on the back of the speedo. When you first switch on, it rises to 12V then back to zero. When the back wheels starts turning, there's an AC Voltage of between 7 & 8V which rises in frequency with the speed. I didn't have a scope handy so I don't know what kind of waveform it was but it gave me the confidence to try another speedo head. Thanks to the really helpful folks at Motorworks, I got a secondhand cluster the next day and bingo! all is good. FWIW, I stripped the old cluster down the the pcb and couldn't see any corrosion or damage whatsoever.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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