False speedo readout

[Zaz]

First post - be gentle :)

Just got hold of a lovely nc23 'k' which appears to have had an overlay fitted to the speedo clockface to show MPH as the main figure with KPH in smaller letters. Either that or different clocks have been fitted at some point, though the odometer and trip counters still read in km's.

The sprockets have also been renewed at some point too, but we cant seem to determine if there has been a drop or increase in tooth numbers.

The problem i have is the speed readout is inaccurate, actual 30mph reads as 20mph on the clock which is obviously wrong, similar readouts at 50 and 70mph, where i rode alongside a mate using his bike and another in his car to test this.

The cable leading to the back of the clock doesnt appear to be damaged, it turns freely and doesnt stop under finger pressure when in gear. It also sits nicely in the slot at the back of the clock.

Not sure what to check next, any ideas ?

[scratchin]

your sprockets should be 15 tooth front and 42 tooth rear, i would have thought the overlay is positioned wrong, i would get a speedo converter and remove the overlay this would also remove the speed limiter

[leopard_pagan]

^^^^^ what he said^^^^^ those over lays are crap.

[Zaz]

Thanks for the replies, i'll take the clocks apart and have a look at adjusting/removing the overlay.

On a related note, anyone know where i can get a mechanical speed converter, my searches are fruitless so far

[Wozza]

Here's one http://www.twowheel.co.uk/motrax-mechan ... rters.html" onclick="window.open(this.href);return false;

[leopard_pagan]

no need to remove clocks for the over lay. it SHOULD be stuck on the out side of the glass.
fit a manual converter, far easier.

[Wozza]

Obviously you'll have to make a note of when your odometer stopped reading kilometres and started reading miles.

[Zaz]

As far as the overlay is concerned, i dont see how one fitted to the outside of the glass would work as the needle is inside the housing and would not indicate speed that way. The clock face is white whereas any original faces i have seen so far are all black, hence the idea that it is an overlay or replacement clockface.

Also, thanks for the link to the converter :)

[Matchlessman]

Hi Zaz,

Some of the overlays you can get are transparent and just have the mph round the outside. These go on top of the glass.

It sounds like your one is stuck directly onto the speedo face, the needle runs over the top of it? If so, then yes, its going to mean taking the clocks apart.

You might also have problems getting the speedo to read correctly either miles or K's, whoever put the overlay on in the firstplace didnt put the needle back on in the right place.

And easy solution might be to speak to Graeme France and see if he has any speedo's in stock.

[Zaz]

I had the clocks apart earlier, always fun to strip panels off and find whats what with a new bike :)

Seems to me that the clock faces themselves have been replaced at some point, all three are labelled 'seespeed' which suggests to me they are aftermarket.

That converter link came up empty but ill keep searching.

Thanks for the ongoing help :)