Speedo speeeeeeeeding

[kramdra]

Hello again. My bike sees to be in here a lot recently

Have some problems with the speedo. *note* I done the front brakes this week, what have I broken? :o

I would expect if it were the cable, for the indicated speed to drop not increase!!! The cable did come out of the sheath. Also I cleaned the gear and put fresh grease in.



So I was going down a steep hill and actually managed to get the bike to 70! this being quite an achivement I was looking at the clocks.

Then it quite rapidly moved upto 90+ mph.

I slowed down quite a bit, but the speedo sat for 15 seconds... then slowley dropped back to about 55.


This only happened when I was pushing the bike near 70, its repeatable (if I can find a steep hill ). On the way home, at about 30, the needle was jumping around.

Also, is a speedo fail = mot fail? got a few months left...

thanks
Mark

[Ichy]

Speedo isn't checked on as part of the MOT.

Worth checking the cable is routed correctly, it sounds like something is sticking. Did you check the speedo drive was seated correctly against the fork leg?
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[kramdra]

the cable looks routed ok. Also when I had the cable out, it looked in good condition - not worn/frayed/rusted or anything.

How can any component - hub gears, fork drive, cable, square drive.... spin faster than the wheel?

I think the clock must be faulty, but they are not cheap :/

thanks
Mark

[CaNsA]

Check the cable,

The zxr said to me "140" when i was in 2nd gear crawling though traffic.

If the cable is defo fine then the speedo drive is fuxord

[Billing]

make sure you've got the tabs in the hub engaged with the ones in the wheel, if they're slipping and then catching they'll play havoc with it, had a similarish issue on my CG when I did the front wheel bearings
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[Martay]

Sounds like the speedo unit i think.
Check the hub and cable first though, they're cheaper!

My 125 would say 30mph at walking speed, and it would shoot round off the clock as speed increased. The numbers stopped at 80, but it would go round to the end-pin at 0.
Then when i stopped, it would fall back down to 30ish and stick. Had a new cable but it was the speedo unit itself gone bye-byes
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[Teflon-Mike]

The speedo needle is pulled round the dial by a magnetic 'clutch' for want of a better description, resisting a spring.
As the wheel turns faster so the magnets under the needle turn faster, pulling the needle round more against the spring.
If the cable is fitted badly or is worn, it can 'wind up' so the speedo will under read, then as the cable unwinds, it will over read. Often gives wobbly needle syndrome.
Inside the speedo itself, wear on teh shaft, crud in the workings can all cause anomolouse effects.
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