Bike sit too long?

[rainycity]

Hey guys,
Sorry I haven't been around for quite awhile but I suffered an injury in 2017 and have pretty much been down until just recently.
But enough feeling sorry for myself.lol
My 81 sat for close to 2 years because I haven't been able to ride and I finally got her pulled out to do some much missed riding but now I think it's a little pissed at me like a teenager with angst and is giving me one of those, I'll show you attitudes.
My problem, first thing was my starter button fell out so I need to replace that.
(I just used a pencil)
But the one problem I do need to fix is my headlight just quit after I shut the bike off and then started it up again and i cannot for the life of me figure out why.
I did the obvious and checked the fuse, changed the bulb etc.
The tailight, turn signals, brake light all still work but the darn headlight wont.
Any ideas?

 

[lakeview]

Headlight as built may only work when it is running.

 

[rainycity]

Headlight as built may only work when it is running.

I wondered the same thing so I tried it both running and off.
I just noticed the black wire going into the lamp plug is discolored but I dont anything at all about auto/motorcycle electrical systems. I did look at the wiring as best I could. I think maybe tomorrow I'll pull the tank and try tracing it back.

 

[gggGary]

But once the headlight relay latches it (should) stay on until the main switch is turned off.
Black wires are ground. Easy to mix up black, dark green, and brown wires that all live in the shell.

 

[rainycity]

Headlight relay latch?

 

[gggGary]

Some what enigmatically called the starter cut off relay, it also controls the headlight. I think this diagram over simplifies the internal design, the headlight control is a separate relay from the starter shut off section.
Turns headlight on when when alternator starts to charge via the yellow wire out of the stator.
If not restoring, many eliminate the "reserve lighting unit" which oxymoronically seems to have a higher failure rate than the headlight it is supposed to safeguard.

 

[MaxPete]

Easy to mix up black, dark green, and brown wires that all live in the shell.

Yup - that is a very tricky thing on these old bikes. There are three wire colours that all look the same: black, brown and “chocolate” and it caused me a huge amount of grief because I’m a bit colour blind (like most left-handed people it seems).

I must have gone through three boxes of fuses during the resurrection phase as a result.

 

[rainycity]

Thanks for the help. Here goes nothing.lol

 

[rainycity]

Hey, is there any way to bypass that stuff and wire the headlamp direct or is that not a good idea because I'm just lost here.lol
Here in Washington state it is required to have your headlamp on at all times which is something I would do anyways.

 

[XSLeo]

The safety/headlight relay is tripped by a voltage coming of the alternator on a yellow wire. This wire only gets voltage when the alternator makes voltage. If your alternator isn't working then your headlight won't come on.
You can check to see if the alternator is doing it's job by checking battery voltage as the bike is running. Check voltage at idle, often 12.5 to 13 volts. As you increase rpms the voltage should climb up to about 14-15 volts by about 2-3000 rpms. Rpms above this range the voltage should not go any higher.
If your voltage doesn't climb as you raise rpm's then your alternator isn't working.
There is a Charging guide on here. can't do links very well but if you look up near top of page and find click on where it say TECH it will take t a list of topics. Such as Electrical. Under Electrical look for the charging guide.
Follow the steps to find out what is wrong.
Often cleaning the rotor slip rings and new brushes fixes it right up. You may need to go through some of the wiring checking connection. These need to be clean, as in bright and shiny. Tighten as needed to get good connections.
Leo

 

[XSLeo]

There are several devices that can be bypassed. The RLU is one. This basically lets you know the low beam is blown on the headlight.
The light checker, this tells you your brake light is blown.
If you search the TECH section you can find threads about these things.
Leo

 

[MaxPete]

I think that the "headlight on" rule has been pretty universal everywhere for many years.

As Leo said - you can bypass the RLU headlight safety device quite simply - just look it up using the search function and you will find that it requires a simple jumper in the device connector.

The pre-1978 bikes (and perhaps somewhat later as well) had an actual headlight on-off switch on the RH handlebar switch cluster and I find it useful if I am trying get into the garage without waking the neighbours late at night.

Pete

 

[rainycity]

Thank you guys, I tried a few things you guys suggestedand it works again. Time for a ride.
Thank you again

 

[fredintoon]

Yup - that is a very tricky thing on these old bikes. There are three wire colours that all look the same: black, brown and “chocolate” and it caused me a huge amount of grief because I’m a bit colour blind (like most left-handed people it seems).
I must have gone through three boxes of fuses during the resurrection phase as a result.

Hi Pete,
all the world's great men have been of sinister dominance, You, me and Leonardo DaVinci for instance.
But I didn't know of our link to being partially colour blind.
Although that does better explain the 1/2 box of fuses it took me to connect a turn signal than my own supposition
that it was too dark inside the headlight shell to see the difference between a black wire and a dark brown one.
But there is a solution. Switch to pre-1970s Britbikes. They are wired up Positive Earth so all their grounding wires are bright red.

 

[MaxPete]

all their grounding wires are bright red.

YIKES - RED ground wires....I guess that is why they drive on the wrong side of the road....

 

[rainycity]

Hehehe

 

[XSLeo]

What things did you try and what things worked?
We need closure.
Leo

 

[fredintoon]

YIKES - RED ground wires....I guess that is why they drive on the wrong side of the road....

Hi Pete,
riding or driving on the left ain't wrong, it's a British tradition.
Brits rode on the left in medieval times as it allowed a person to have his sword arm facing a potential enemy.
The French rode on the right in medieval times so they could hide behind their shields.
Then, as now, us lefties just had to cope with a world that's put together backwards.