A50CC restoration

[berniej]

Wot! No speedo drive!?

Spent today doing further spannering and examining and couldn't find the speedo drive....
I know it's a competition model and guess that explains it - but my parts book seems to only show only 68-0534.

So, were there actually three variants? Speedo drive only, Speedo + tacho drive and tacho drive only?

I'll have to have a think about alternative options for driving a speedo - any suggestions please?

Cheers,
Bernie

P.S. Thanks for the tip about using aluminium foil around the fork legs Mike - I did that, applied a bit of heat and a few mild expletives and the lower stanchion bush retainers gave in 

[Mike Farmer]

 

Glad the foil worked. I have no idea why it should do so.

Speedo---Electronic. However it can throw up some probs if your bike is still Pos earth. I'm just going through it with my trike. In fact we are beginning to think that the best way to go will be change the earth to Neg. No big job just a bit time consuming. I'm just about to put my long term(very) Thunderbolt on the bench and that will be done neg.

Mike

[berniej]

-ve earth should be no probs! As this bike doesn't have a battery I can make the earth either polarity. -ve will also be best for LED lighting I think.

Cheers,
Bernie

[DAVE BRADY]

Hi,

I recently changed from + to - earth to fit an electronic speedo.  I think all I did was change the battery leads and the connections on the coils. The lights work the same either way so only ammeter to swap round as well if you have one fitted.
The speedo is one of the Smiths ones and is an exact replacement for the original and has a pick up that can be fitted to either wheel as it works on wheel revolutions.  Not that cheap but looks good.

Dave.

[berniej]

Dave, does your speedo also have an odometer display?
I've found a few speedos but not many have that....

Cheers,
Bernie

[DAVE BRADY]

Hi Bernie,

Mine has total mileage and trip can be selected.  It is a replica of the grey faced magnetic speedos and will fit in the mounting rubbers.  It is a Smiths and there are several option as well as rev counters.  They are not cheap but look like good quality.
They are marketed through Digital Speedos who were offering a discount through The Star a few issues back.

Dave.

[Mike Farmer]

 
Was it not necessary to change the ammeter connections. I guess if you have a solid stae rectifier you would also need to change polarity there?

Electronic speedo---there are a couple on the market with built in battery that just clip on the handle bars.

Mike

[berniej]

I was hoping to avoid fitting a battery, just use a rectifier/controller on the two ~6V lighting outputs and power instruments from there.

However, I think I'll need to talk to instrument suppliers about that as the DC voltage still might not be sufficiently 'clean' and steady without the buffering effect of having a battery fitted.

Cheers,
Bernie

[DAVE BRADY]

Hi,

I do not have an ammeter but an LED voltage monitor instead and as the earths are all back to the battery it all changed at the same time.
The battery speedos that clip on the handle bars do work well.  Get one that goes up to 99mph and they have things like total mileage, trip, highest speed, average speed.  Not too easy to see the numbers in bright sunlight.

Dave

[berniej]

Many thanks. I've emailed digital speedos to see what they say about powering without a battery.
Do the 'clip-on' battery powered speedos just use GPS to determine speed?

Cheers,
Bernie

[DAVE BRADY]

Hi,

The clip on bicycle type use a magnetic pick up on the wheel.  The Smiths ones can have the wheel sensor like I have fitted or there is a GPS option

Dave.

[Mike Farmer]

 

I'd only considered GPS type.

Mike

[berniej]

Had a reply from digital speedos which was very informative. Their Smith's replicas need 12V so probably not so straightforward for this bike.

Although.... there are two separate AC outputs for the lighting, one for brake light and one for the rest. I wonder if I could get sufficient AC output to rectify to 12V DC by using those together.... probably needs some experimentation - I should have put 'an oscilloscope please' on my list to Santa.

They also sent me a link to this which interested me although rather expensive. https://www.digital-speedos.co.uk/gauges-c4/motorcycle-gauges-c27/speedometers-c31/battery-operated-gps-chronometric-speedometer-125mph-p875

So a clip-on GPS version would maybe keep me legal while I investigate other options.

Cheers,
Bernie

[DAVE BRADY]

Hi,

That 'Chronometric' stye looks good and with a built in GPS is compact and means even less wires to keep tidy.  The details did not give a size but it looks like direct replacement.  I might consider one of these for my other bike which currently has a foreign speedo fitted.

The cheapest option for a temporary speedo is probably the clip on type with a sensor that goes on a wheel.  I think you will get quite good one for less than £20 with mileage, trip, average speed and maximum speed, and a clock all built in.

Dave.

[berniej]

There's also Hans Beck from whom I bought a speedo for my M21 some years ago.
You need to supply your own can and there's no odometer but otherwise they look quite original....

https://www.beckelektronika.nl/snelheidsmeter.html

Cheers,
Bernie