Lights & Gauges - Brighten and Dim a bit ???

[getsum]

I have recently bought a 78 GS 1000

I rode it in the dark for the first time last night.
If it idles all the lights work fine.
When I rev the gas or when I ride the lights are brighter.

As I rev in neutral -
As the RPMs go up - the light brightens
but as the RPMS go down to idle the lights dim a little.

They are still bright when idleing - but you can se a difference - WHY ??

Is the some thing to worry about or am I alright ?

[MinnesotaTim]

I haven't dug into the GS electrical system yet, but on ATV's and snowmobiles the output of the regulator does change a bit with engine RPM's as the stator will put out more power at higher engine speeds. Thus as you rev the engine, the lights will get brighter because your system voltage is going to go up. I believe thats the same thing that you're seeing on your GS. If you could get someone to be an extra set of hands for you, put a multimeter on the battery terminals and check the voltage at the terminals at idle and then when you rev the engine. If you see the voltage go up with RPM's then you know whats going on.

- Tim

[wiredgeorge]

Large voltage variations are unacceptable. The lights dimming can be a symptom of this. To check, measure your battery voltage at idle. It should be around 13VDC or so. Then, rev the engine to 4K rpm and check with the engine speed up. You should have a tad less than 15VDC. If you have considerably higher or lower, your regulator/rectifier are suspect. This device makes sure the output of voltage is consistant and may be failing. Suzukis have long been notorious for hiding the reg/rec and allowing heat, over time, to fry this device. A reg/rec lasts longer if remounted in the air flow as opposed to hidden in still air. You may have a variation in light intensity due to engine speed (higher voltages at higher rpms) that is acceptable but it is worth checking the regulator/rectifier to find out if a problem is coming on...

[getsum]

Bummer

VOLTAGE REGULATOR?
Is that what you are talking about ----

I knowI sound like an idiot mechanically now.

Is that the same thing as a STATOR ? I hear that word a lot but do not know.

[renobruce]

The stator is the generator which is under the left side engine cover. The regulator/rectifier is the ribbed little "box" next to your fuses. I would do like the others mentioned.. check your voltage at idle and 4K. A little dimming and brightening is normal. Alot is not good.

[kalessin]

Also see my reply to your post in the general "Discussion area" forum.

The stator is kind of like an electric motor (like the one that runs your washing machine), but if you turn it using an external power source (your bike's engine), it generates alternating current, assuming something bad hasn't happened to it. It has three outputs, and if you measure between each output when the motor is running above about 2800 or 3000rpm, it will generate 70v alternating current between each of the three output wires. (you can measure it with a voltmeter, just like you could measure your house current at the outlet)

The three output wires go from the stator to a regulator/rectifier. This is two functions combined into one. The rectifier stage is first, it converts the 70 volts AC to about 18 volts DC. The regulator stage limits the voltage to about 14.5 volts DC. This 14.5 volt output is put into charging your battery, until the battery is full, in which case the electricity (energy) is bled off as heat, which is why regulator/rectifiers have big heat sinks.

[getsum]

Kalessin

Dude - You are the man.
I appreciate the input on this.
I understand the whole concept now.

I figured it was something like that but being a LAYMAN - I had no idea.


THANKS AGAIN.

I willcheck it out.
I might PM you and picjk your brain if you don't mind once I figure out if the voltage is too high or not.

THANKS.

[MekaniX]

1978

Doesn't everything below 1980 have a separate regulator/regulator ? If so

what you have is a 3 phase rectified and separately regulated charging system.

at 1000 rpm its drawing power from the battery about 10 amps

at 2000 rpm you're charging system is making the exact amout of power you need , so power being drawn = power being made = no loss

above that rpm, the rectifier kicks in and all you're doing is charging the battery since you're making plenty of power and not drawing enough current to bring the voltage below 14.4 v.

at 5000 the stator cannot give anymore power, basicaly the magnet is moving too fast and the stator is completely saturated.

if you measure the voltage at 1000 than 2000 than 5000 RPM

you should get something like 12.5 than 13.5 than 14.4 idealy,

IF however you only get 13.5 v at 5000 rpm or around there , that could mean that one of the 3 phases are not working ,, basicaly one of the diodes in the regulator is fried but the others keep working and make it seem like nothing is wrong.


just my 2 cents , hope it helps .

[Jackrp]

[QUOTE=MekaniX]1978

Doesn't everything below 1980 have a separate regulator/regulator ?

Yes, BUT with electrex it can be converted and simplified with a regulator/rectifier unit and made much more reliable, Bike Bandit has good prices on eletrex,(better than the electrex site itself) and cheaper shipping prices.I should know, just bought 2 in the past month,(not for the same bike)

[getsum]

I looked at the bike and checked the voltage.

It stayed at 12.5 the whole time.
Whenever I reved it to 4000 or idle.

I took the cover off.
It has 2 seperate ribbed boxes.
One square - one tall and skinny.

So it does have "2" seperate r/r

Also- I took the positive cable off of the BATTERY.
The bike stayed running.
Is that a good or a bad thing ????????????

Anyone have any ideas of a good place to get the R/R for a 78 GS1000 ???

[MekaniX]

I'm familliar with the electrex unit however, i just wanted to know what system we were dealing with, IE RR in one or separate boxes

so it seems stock.

voltage could be normal

keep in mind that its older technology and maybe its designed to stop at 12.5 v

Just a bit of advice, if you have a charging system problem or ever encounter one, don't rev the engine with the battery unplugged ,

idle is ok because the charging system is making just enough power and not too much

but if the battery isn't there to keep the voltage down in the case that something fails (ie regulator) and the engine is reved, well say good bye to to the electrical system :shock:



the whole system could be running as its suposed to, at 12.5 v

an electrex unit will let the voltage climp to 14.4v i beleive

then you may notice and even bigger difference with lights dimming at idle

a jump from 12.5v to 14.4 v off idle would be quite noticeable

hope this helps

good luck

[Jethro]

Just food for thought, 12.5 is a 50% discharged battery. 12.7 is 100% charged when we are talking a non-sealed battery. Sounds to me that even if the charging system is checking out, your battery may be bad.

[MinnesotaTim]

If when reved up the charging system still only put 12.5V through to the battery terminals, I'd suspect the stator and/or regulator/rectifier. Unless, of course, these old systems are actually designed to work with a 12.5V charging voltage. That seems pretty low, though.

Anyone else out there with the same bike available to check their system voltage for comparison? Or does anyone have the specs on this electrical system?

- Tim