Li 150 brake light

[bazza3004]

Hello
I have just rebuilt an imported 1966 Li 150 and have now got the lights working. The scooter is still on 6v points ignition (no battery) and whilst the headlight and tail light seem to be bright enough considering the 6v system the brake light is only about as bright as the rear tail light when lights are on. it seems to be ok when lights are off though.
I have double checked the earth from the rear light and cant see anything untoward on the headset side . I have checked the wiring with my multimeter for continuity and all seems ok there, I also have the correct rear bulb ie voltage and wattage. the only thing I haven't connected on the lighting side is the speedo bulb and that's due to this being missing when I bought the scooter and have forgot to buy one . is there something else I should do or check or am I just expecting too much from the old 6v points system ?

[Meds]

Have you cleaned up all the connections

[MK Monty]

Have you got the brake light connected to the brighter filament you may have the rear light on the Bright one and be happy with how bright it is until the brake light comes on. They are normally something like 5W 21W, swap the wires over

[Wack]

The brake circuit has its own coil on the stator,pink wire. Check its voltage as mine was very low.

[bazza3004]

Thanks for the replys i will double check the wires are correct on rear light and if i can work out which setting i need to turn the flippin dial to on my meter il also check the output on pink wire. Should it just be about 6v or is there more to it than that ?. Thanks again.

[dickie]

Also, when you check for continuity you may get the false impression that everything is ok if you see a low reading like 1.5ohms, but as the current in the stop light is something like 3 or 4 amps, that would mean you only had about 3v on the lamp.

In other words meds' advice is good.

[Meds]

Here are a couple of things to try(depending on what kit you have)
Clean every connection till they are clean and shiny including the wires and the connector blocks brake light switch connections and the bulb.
I use emery cloth or a fibre pencil
Tighten all the push fit connections and make sure they are all good firm connections and not loose.

Check the resistance of the circuit from the pink wire going into the connector block all the way through to the back light bulb tang( little bit that connects to the bulb) and change the state of the brake switch when doing this as the switch is likely to be 50 years old and not on perfect condition. The resistance should be less than 1 ohm with the pedal down.
If the resistance varies when the pedal is down its possibly the switch.

Check the voltage on the pink wire from stator with it disconnected ( meter reading AC volts, set to somewhere around the 20v scale) you should get 9v ish which will increasing as you Rev the engine.
Or
Just connect the pink wire to a brake light bulb and Earth the bulb on the engine, see if it's brighter, if it is the high resistance is somewhere in the circuit.
If you have a rear light with the removable bulb holder (not carello) use this to connect straight to the stator pink and earth it to the engine see what you get

[bazza3004]

Some good tips there thanks. I will try the things you have mentioned i have got a spare new switch to try . I will get some time to look at it before i go to work and will let you know how i go on. Thanks again fellas.

[Meds]

Check the new brake light switch fits correctly
My aftermarket ones didn't and I had to bodge one up

[bazza3004]

Cheers meds il double check that.

[bazza3004]

Not had much time last day or so but did manage to try new switch and it was no different. I also connected rear light unit direct to pink fro stator and earthed it and it was much brighter. I will have another play with it tomorrow and report back.

[Meds]

[quote][/
Re: Li 150 brake light
Post by bazza3004 » Tue Apr 28, 2015 9:27 pm
I also connected rear light unit direct to pink fro stator and earthed it and it was much brighter. Iquote]
From this it sounds like your sator and light Unit are ok.
Sounds likely that their are dirty/bad connections in the rest of the circuit.
Good luck

[bazza3004]

thanks meds im going to have an hour on it now before I have to go to work, I will let you know my findings. thanks for the help/advice. baz.

[bazza3004]

I tried different bulb holder and it still same. Front and rear lights are fine but brake light only just lighting up very dim. I took the wire from headset to rear light off and put a fresh length in its place . I disconnected pink from switch and rear light and also replaced this with a fresh length. Both these didnt resolve the problem. Ive ordered replacement headset junction box and rear frame leg junction box and will see if these make any difference. Il make a new coil- frame - engine earth lead whilst im on with it. Its starting to bug me now

[bazza3004]

Should have added i also put a fresh length of wire from stator pink to brake light switch.

[Meds]

Have you tried bypassing the brake light switch by connecting the 2 pink wires together to see what you get.
It might prove either
1 the wires are fine and it's the switch/ connections
Or
2 the switch is fine and it the wires /connections

The other thing to try is measureing the voltage (with the brake light on ) at
1. The stator output pink into the connector block at the back
2. The connector block at the back output pink
3. The input into the brake light switch
4 the output from the brake light switch
5 input into the brake light holder
6 the brake light holder earth ( this should be zero)
Try and use the same earth point
on a healthy circuit the voltage measures at 1,2,3,4&5 should be pretty much the same
If there is a significant difference in voltage 1to2, 2-3, 3-4, 4-5 or if 6 is reading more that zero then that's where the problem lies.
sorry if this is a bit noddy as I don't know What your electrical knowledge is
Good luck

[bazza3004]

Lol noddier the better meds . I will do the tests you mentioned . Think it has to be a problem in the wiring somewhere after the rear j box as if i plug light direct on to stator pink and earth it its as bright as a bright thing.

[Nigel. S]

If Med's test results are ok but you still perceive the same problem then I'd be wondering if you're expecting too much from your rear light on your 6v AC setup.
My scooter is also 6v points ignition and as long as my engine remains close to standard that's the way it'll stay, but I have done the easy 12v conversion to lights and then run brake light and horn as DC from a battery, with LED rear bulb. Horn is loud and brake light a lot brighter than normal rear light.

Edit just saw your previous post which suggests you may have found a possible cause. hey-ho.

[bazza3004]

Just a little update. I measured the voltage from the pink on the stator. Now i wont swear i had the multimeter on the right setting (far too many choices lol) but i think i did and the voltage reading was 2. Somthing so i now have 2 replcement stators and flywheels to try. I will fit one of these tomorrow and read up on timing up with a points set up(its been over 30 yrs) and see how it goes.

[Meds]

Keep trying
You will get there.