Bernie Kent has a 1971 Norton Commando and has reached out as he is considering putting on indicators (turn signals)

These were optional at the time, as they were not yet law in all countries – so they were on the Norton pricelist and were either factory fitted, or could be added as a dealer fit option.

The following year, the were fitted as standard to all Commandos produced.

Connection

One thing to watch out for when you are fitting Lucas turn signals is the positive feed from the battery (the ground/earth)

This is probably (in my opinion) the worse wired part of the bike, as the stalk on these indicator lamps are made of plastic and are chromed – and Lucas are relying on this for the positive power feed to the lamp!

…so if your lights are flashing to fast, too slow, or not at all this should always be the first thing to check!!!

Lucas Flasher Unit

Bernie has a couple of choices – either to fit the standard two wire flasher unit – this is a mechanical device with a bimetallic strip in it – kind of like the thermostat on your central heating at home.

Although they are good and reliable (they are only starting to fail now after between forty five and fifty years) they do limit your options in terms of lamps.

It is important that you fit 21 watt filament lamps front and rear.

Failure to do this will result in flashers that don’t flash, or flashers that flash really really fast!

If, for example you wanted to fit LEDs, you’d have to use resistors so that they work correctly – which totally defeats the object of using an LED, as with a resistor inline, the power consumption would be the same as the incandescent bulbs they are replacing.

The other consideration is the turn signal warning lamp in the headlight bucket – with LED turn signals, the warning lamp needs to be wired with two diodes, and connected to earth.

The reconfigured turn signal warning lamp will look like this:

Modern Alternative

With all this in mind, I would suggest considering a different type of flasher unit instead.

There are several options available, but I recommend Classic Car LEDs as one worthy of consideration.

They have a solid state unit available, and the option of Positive Earth – so perfect for our bikes.

The reason I like these units is that the same unit will support incandescent lamps or LEDs, so there is a good degree of future proofing.

The unit is a simple canister design, and can easily be hidden away on the bike.

Here follows a copy of the wiring diagram as per their website:

You will note that this has a separate line to the warning lamp, which means no requirement for additional diodes.

Wiring Diagram

Here is a custom Wiring Diagram for Bernie’s 1971 Commando, which shows the above flasher wired in, replacing the standard Lucas two pin flasher module.

As you can see, it is a very simple process to fit.

Custom Norton Commando Wiring Diagram – Bernie Kent PNG 3066×1841