Dimming Tail light 6v 79' XL250

[The Lone Rider]

Perhaps someone can shed some light.

Problem: Tail light & neutral light flashing/dimming when indicators are turned on.

Thought was an ground issue, discovered stator was fried. Replaced, tested bike.

Lights running bright and battery showing up and a bit over 7v when revving now.

Tail light and neutral still dims as indicators flash.

Did some research - found a youtube video where it does the same on his much nicer looking 70's XL250.


Is this some sort of 6v or old XL250 thing or is there still some sort of fault to hunt down?

[FJRider]

How old is the battery ... ???

[Ginge09]

To be fair they were never strong in the lighting department from new.

If the headlight is good but the indicators suck the power I’d be looking at the indicator grounds. Maybe run dedicated earths if it doesn’t already have them.

LED conversion bulbs will help. Read the Brit Bike forums. They are six volt with poor charging. They have the work around sorted out.

[The Lone Rider]

How old is the battery ... ???

it is brand new

[husaberg]

Perhaps someone can shed some light.

Problem: Tail light & neutral light flashing/dimming when indicators are turned on.

Thought was an ground issue, discovered stator was fried. Replaced, tested bike.

Lights running bright and battery showing up and a bit over 7v when revving now.

Tail light and neutral still dims as indicators flash.

Did some research - found a youtube video where it does the same on his much nicer looking 70's XL250.


Is this some sort of 6v or old XL250 thing or is there still some sort of fault to hunt down?

likely only a general lack of electricity output of the std system.
If it is The headlight will be diming as well.
Thats just part of the charm of the older bikes.
If ithe headlights not dimmingvsame as the Headlight check for bad insulation in the harness and or poor connections and as you said poor grounds.
Look for voltage drop/Resistance and try running a temp ground.
them take apart the indicator switch and chect the contacts.
you could also remove the headlight bulb to see if its just a lack out electrical output.
Fun times ahead general troubleshooting stuff like this is covered in Haynes manuals Clymer etc. Along with specs and outputs for individual models.

[Ginge09]

So new battery and new stator. If it’s charging okay and the lights work okay then I’d be looking at the wiring.

Indicators do suck power on a six volt system. What’s the flasher relay like? Might be robbing some amps if it is old and crusty.

[The Lone Rider]

likely only a general lack of electricity output of the std system.
If it is The headlight will be diming as well.
Thats just part of the charm of the older bikes.


So you reckon it could just be a shitty old design and inherent in the bike itself? Like I said, I you tube searched for similar year and model and it was doing the same thing on that guys video.

I need a new globe for headlight, but from what you're saying if headlight dims with indicators then its the system?

[husaberg]

So you reckon it could just be a shitty old design and inherent in the bike itself? Like I said, I you tube searched for similar year and model and it was doing the same thing on that guys video.

I need a new globe for headlight, but from what you're saying if headlight dims with indicators then its the system?
I would see if it still dims the tail without the headlight bulb in and visa versa
Those old trailies had f-all charging output.
I would invest in a Hayes Manual and check the output.

[FJRider]

I need a new globe for headlight, but from what you're saying if headlight dims with indicators then its the system?

I used to own an XL250 (grey tank) but it was quite a few years ago. A lot of the (now) older motorbikes with the 6 volt systems could only have the headlight working if the engine was running. As such ... the dimming of the tail-light would (only ??) possibly occur if the engine was not running and no charging current going into the battery ...

I can't recall if the XL's were this way.

[The Lone Rider]

I used to own an XL250 (grey tank) but it was quite a few years ago. A lot of the (now) older motorbikes with the 6 volt systems could only have the headlight working if the engine was running. As such ... the dimming of the tail-light would (only ??) possibly occur if the engine was not running and no charging current going into the battery ...

I can't recall if the XL's were this way.

Dimming occurs with engine running.

[FJRider]

Dimming occurs with engine running.

Then the dimming would be more due to resistance (read corrosion) in (literally) the wiring than an Earth issue (in my opinion).

Maybe ... jury rig a very basic wiring "loom" for the indicators and see if the issue persists.

[The Lone Rider]

Then the dimming would be more due to resistance (read corrosion) in (literally) the wiring than an Earth issue (in my opinion).

Maybe ... jury rig a very basic wiring "loom" for the indicators and see if the issue persists.

Could be. The owner has had the bike sitting since the 90's and gave it to me to get going. All my usual systematic way of going about bikes has failed me on this though.

[FJRider]

Could be. The owner has had the bike sitting since the 90's and gave it to me to get going. All my usual systematic way of going about bikes has failed me on this though.

Corrosion is usually worse near connections, joins, plugs and damaged wiring. There are devices that can test for resistance/voltage etc.

Good luck.