Positive earth indicators?

Your thoughts look about right.   

"B" = Battery.

"L" = Lamps.

If you have a multi meter with a diode test function use it to determine polarity.

Yes, just swap the wires round and it will be ok.

I’m sure the person who wrote B for battery on it assumed that would be from the + side of the battery.

I wouldn’t be at all surprised if connecting B to a negative live and L to the lamps destroys the flasher unit immediately.

I use a similar (but orange coloured) flasher unit on my -ve earth bike.  B is fed from a switched + live.

Michael - but that is not what is being suggested.

Yes - it is safe to assume that B is Battery and L is lights. and 'normal' is negative earth so the B will be positive feed from the battery and the negative will be through the lights.

For positive earth, the B needs to go towards the lamps and the L towards the battery.

Thus the B is still getting the positive feed and the L is getting the Negative.

I think the potential difference across B & L will be the same.

Yes, the electrons don’t mind if they are going uphill or downhill.

The supplier of this flasher is the correct company to contact, if they cannot tell you then the part is not fit for purpose and you get your money back. There is a great deal of these units available so find some one who understand what they are selling.

When these units had LUCAS written on them, and that meant something then these units were Bi metal strips and hence polarity was NOT an issue. IE you ignored polarity. It would be normal to expect there being an 'earth' with any modern Electronic unit. At this cost though we could be experimental and 'see what happens' if you connect it as you want. IF it fails then you return it for money back. But this 'orange' unit is 'digital' which infers it is Electronic, but this 'might not' be polarity conscious. Watching with interest.

I think it should work. At £3 it's worth a shot.

The makers pile them high and sell them cheap.

It is not worth their while to even care about a small number of eccentrics arsing around with antique bikes. Adapting it to non-standard conditions is your project, not the Manufacturer’s.

If you use the diode function on a multi meter the electrons will only flow in one direction, same just using the continuity function.

You should also take note of whether the reading is telling you which polarity is flagged up +/-.

As the guys above are suggesting for three squid you can carry out all of our input as an experiment taking notes as you proceed and learn a great deal from the experience.

As you have no idea what is inside, the diode test will tell you nothing.

just do as I said and swap the wires round.

With a two pin flasher unit, don’t get hung up on whether your bike is positive earth or negative earth.

The flasher pictured is plastic, with no connection to ground.

The B (battery) and L (lamp or load) probably doesn’t matter if the battery side is positive or negative.

As an example, take a look at the pic for a Commando.

Someone wanted to retrofit turn signals to his bike, so I split out the factory wiring for turn signals only - it makes it easier to work out.

In this example, the W (white) cable that feeds the flasher unit is the ‘B’ terminal.

The LG/N (light green and brown) cable is the ‘L’ load terminals that goes off to the turn signal lamps via the left/right switch.

As a reminder, most of these have a wattage dependency - for example, the Lucas unit fitted to the Commando needs two 21 watt lamps as load.

If you don’t adhere to this requirement, the lamps will either flasher too fast, or they will stay on, prematurely shortening the life of the flasher unit.

Ian send me picture of this unit you took apart (inside bit) and I can probably tell you what it is)

Michael-yes the sellers do 'pile them high and sell them cheap' but that doesn't stop the basic function as with ALL items-'fit for purpose'

Now that they’re working, don’t forget to cancel them after the turn.

Ian, you said your flasher was two pins!! BUT it is three!! Also this is real electronics, Integrated Circuit (chip-IC) electrolytic capacitor. They all need the electricity to be the 'right way round' Or there is 'trouble in camp'. Ian by the way that 'big coil' is a relay. On their own a relay does not have any polarity, but they are suseptable to Voltage and the voltage must be DC. Some times you find a relay for use in a modern cars becomes polarity conscious as it has a diode fitted.

The original old aluminium bodied LUCAS FL 8 (I think) will work anyway round as Al says. mine is now 49 yrs old (had commando from new) with no probs, and they cost buttons to replace !!!!

t does seem very complicated to perform a simple function. With the original Lucas Bimetal strip flasher they were very cheap/simple. The flasher rate was quite variable, the MOT/safety requirements showing this with variable Flasher rate. Also these basic units were very dependant on lamp load 2X21W in our case. This would mean that the loss of a lamp or extra lamps would stop the flash rate. So adding a trailer or 4X flasher would not work-you needed another flasher unit. The larger unit seen above will be very constant on its flash rate (due to having ICs) and it should handle extra flasher lamps with the relay. ie 4X, but it will be polarity dependant.