MKIII LED conversion

Please be aware of some points with LED. The LED-Light Emitting Diode, is polarity conscious, and most that are sold are made for Negative Earth. There is no need to change the bike's  polarity but it could be an option-more information if you contact me direct.
You need the specific Flasher relay, as the current drawn by the LED is so small the original flasher will not work.
The wiring colours of the wires can be unusual, so have fun with the fitting and making them work.

Hi Jerome,
as the part numbers given are for an LED flasher and associated LED's then these will work on your commando.

On the MK3 you may also need the 'tweeker' or rearrange the wiring. if you use the tweeker then set it up with the bike running. They are so sensitive that if you set them up with the bike stopped then it will flash like mad when it is running. Best of all is not to botehr with the conversion of the headlights and stick with just converting the headlamp and the tail light. 

Sorry Ashley, where did the headlight / taillight come into this discussion.

You have a couple of options.

My preference is to use a modern flasher unit that has a separate line for the warning lamp.

The other benefit of a modern flasher unit is that you can use LEDs, incandescent lamps, or a mixture of both, as you no longer need to make up the magic 42 watts per side to get the flashing speed correct like you do with the original LU35048 flasher with it's bi-metallic strip.

I did an article about this sometime ago which you may find useful:

https://granttiller.com/bernie-kent

Classic Car Led's do a selection of positive or negative earth flasher units for use with LED bulbs.

They have separate connectors for the LED flasher warning lamp.

Here's one example:-

https://www.classiccarleds.co.uk/collections/12-volt-collection/products/12v-electronic-indicator-flasher-relay-classic-car-with-oe-click-x-l-p-2-3-pin?variant=8299346853983

The original idea for the indicators using 2X21 Watt lamps each side is that the warning bulb being only 2W (low current) gets its earth return via the low resistance (when cold) of the twoX21W lamps on the other side.
Hence when you go to LED this sytem does not work. So we have a 'normal' circuit to earth with a new LED warning lamp, but it needs a diode feed (tweeker) from each side of the indicators to make it work.

All Led are polarity conscious. When you buy them are MADE for a particular polarity of earth which you specify when you buy them. If they they are made for a motorcycle then they need to work. If they do not work then they are not fit for purpose.
BUT if the wiring of your bike is not in good order then the wiring will need sorting, earths need to be correct and 50 year old wiring will NOT be much good.

Some LED can be configured to be Positive or Negative Earth, but not by Lucas as the Lucas company finished in the 1980s. The items you buy in a Lucas box these days are made in the far east under the Wassel name, mostly these products work ok.

The bulb being discussed here is specific to the Lucas 917 lamp unit 'cos it has both white and red components.
Even so, it's difficult to see how an LED replacement for a 380 bulb can be compatible with both negative & positive earth wiring - I suppose you could split the 12V in half (6-0-6) and route accordingly with some clever internal circuitry, which might justify the price.

This lot https://www.feked.com/lucas-12v-led-stop-tail-lamp-bulb-917-type-rear-light.html say it's negative earth only. And that looks like the one in the NOC shop. Unless anyone knows better, I'd say this LED bulb is not suitable for positive earth electrics.

And, as a personal note, I can't see much advantage in reducing the power consumption of the tail light from 5W to 1.8W, saving a whole 3W. Might last longer but you can buy 8 x 380 bulbs for one of these LEDs.

On the MK3 the best lamps to replace are the headlamp bulb - use a modern version that is the same length as the standard H4, sometimes these are called compact versions. Next is the tail light, but use an LED tail light board and not a bulb. I would not bother with the indicators, yes they use some power but with a decent charging system and big battery like that on the MK3 there is no point as the indicators are only used briefly - it keeps everything simple. 

Hi Stan,

Re your comment:-
Even so, it's difficult to see how an LED replacement for a 380 bulb can be compatible with both negative & positive earth wiring 

All you need inside the bulb itself is a simple bridge rectifier, so just 4 more diodes, pennies.
Then they do not need to make two versions of the same bulb.