Hitchcocks Forum

Hi, I'm trying to fit the Smiths rev counter to my C5. This is the 2015 model with the ECU - 500 EFI
The fork-top mount won't work because they changed the fork design, that screw now holds the top of the fork leg in and it's a bigger thread. Nevermind I'll fabricate a handlebar clamp.
Big problem is one wire has to go to the coil hidden under the tank. Neither side is earthy and the battery is out. It's ECU so no contact breaker. Loom colours are red/white and orange (coil side is red/white and brown).
Any idea which wire to choose?

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Tabellarius de verbis ostensor gaudium

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The red/white wire (Pin 18, ECU) is the best bet, this is the feed to the coil. in the same way that the points would have been. Sometimes, connectin things like this can lead to problems from back EMF, eddy currents and the like, but if it all seems to run ok, then it probably is.

The orange (or brown) wire (pin 1 ECU) is a common return for the ECU that goes between relays, ignition O2 sensor and other things.



The tacho on the EFI Continental GT runs from both wires of the crank position sensor, but no idea if it would run a Smith's, or even if it is a good idea to try. You certainly don't want the ECU to go bang.



I would suggest the red/white to the coil. the ECU must be man enough to run the coil, so I don't see that teeing in a speedo wire would adversely affect it. Anyone else know if this is an ok thing to try?

for a colour diagram which is easier to follow, click the following, Scaly's RE stuff





















Tabellarius de verbis ostensor gaudium


Tabellarius de verbis ostensor gaudium

Thanks Scalyback, that worked. I've got it working nicely now. Main problem is the handbook wiring diagram doesn't list colours properly. And on the bike - for example - the ignition switch has it red/white and red but where it joins the loom switches to red and red/white; they swapped the colours over. The Smiths does have a connection for ECU but our ECU doesn't have a tacho out. Handlebar clamp was lifted off an old Raleigh m/c mirror and a B&Q t-shaped 75mm "mending plate", without the outer cup (it looks quite neat). The supplied lead on the Smiths tacho is only about 8-in so I needed to add in some joiner wire, The casquette is jammed full of bulky electrical joiners.