Using 12v lights on a 6v system

Is there a way to convert the system to a 12 volt from a 6 volt? If I
replace the voltage regulator with one meant for a 12 volt system will
it work? Can my current magneto handle it?

Its a Yamaha DT100, 1981 with 1900 miles. Thanks
-J

 

It may be possible, but it really, really isn't worth the effort on
something like a DT00.

 

Well, the main problem I have is the bulbs keep burning out b/c of
vibration (thinking those rubber dampers aren't as soft as they used to
be) and the replacement bulbs are expensive. And there are LEDs in 12v
forms that would fix the issue altogether.

The headlight is fine the way it is, i'm more concerned about the other
lights, especially the turn signals and instrument lights.

 

Would it be more involved than simply changing the flasher and voltage
regulator?

I know a 26-year-old DT100 isn't the greatest thing in the world but its
in damn good shape and i'd like to keep it around for awhile.

 

If you do a google search:

"6 volt" LED bulbs

It'll turn up a bunch of sources for 6 volt LEDs.
Lots of old 6 volt autos around.

Or maybe you could connect two six volt
electrical systems in series.

 

rolling your own 6V LED lighting probably wouldn't be that hard, if
you've got much electronics experience. You might also contact a
manufacturer of LED lighting solutions for bikes and see if they'd build
you up some 6V lighting for a reasonable price. Some of those places do
custom work anyway, and it might not be as expensive as you might think.
Just tossing some thoughts out there, fwiw.

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

I really don't know enough about electrics. The DT100 may have a
separate reg and rec or they may be combined. As one who's owned a few
small 6v Yamahas, I've always found that if you buy a good battery and
keep it charged, everything works fine.

The headlight is a bit puny, but that has nothing to do with the fact
that it's 6v.

 

Many micro electrical systems such as yours are designed to closely match
the load of the stock bulbs. Thus, if one bulb is burned out the regulator
SOMETIMES can't absorb/shunt enough of the excess output and the other bulbs
burn out as well. Even if vibration is killing your small bulbs, replacing
them with LED's will overload the other bulbs, such as hdlight because the
LED's have very low consumption compared to the incandescents. These systems
must have all loads in place to operate correctly. i.e. all bulbs and a good
battery connected. Removing the regulator might let her get up to 8 or 9
volts at full scream, but not 12. Check your voltage at high rpm. If it's
more than about 7 you need to add more load to keep it down, like another
bulb, a resistor, or check the ground from your regulator. I think you are
better off to work with the stock system than re-invent the wheel (yet
again). Krusty??

hth

Hank

 

I think you're right --- my bike actually does not have a voltage
regulator at all, and it doesn't appear to have had one from the
factory. My voltage is swinging from about 3 volts at idle to over 12 at
redline. However I think on this bike the headlamp is on its own circuit
and independent of all of the other lighting.

Thanks for the insight.

 

You can buy 6 volt LEDs to fit standard sockets.

I repeat, you can buy 6 volt LEDs to fit standard sockets.

http://www.google.com/search?hl=en&q="6+volt"+LED+bulbs&btnG=Google+Search

Buy some frikkin 6 volt LED bulbs. Plug the frikkin 6 volt LED bulbs
into the frikkin standard motorcycle sockets. Leave the frikkin
magneto alone.

 

If the bulbs are black inside after 'burning out', you may have
a bad connection (intermittent open) between the rectifier
and the battery, which includes the 'ground', (the frame and engine).

Those days Japs fitted a tiny generator that had just enough beef to
get the full load
going. With no lights on, the poor battery was used
to keep the voltage maximum around 6 plus a bit volts.
When the battery is (momentarily) disconnected,
the tiny generator cries: "hurray, I can now make more than
6 volts", and by doing that, blows out any bulb
that is on at the moment.
I had that on my SuZi GT250. (Had a 12V system, but the same sort of
'tiny generator' setting)

When you mount LEDs, the generator will put
more amps into your battery. And that battery will
be bubbling all the way untill all juice is gone.
I once had an empty battery (totally empty I mean), and by wife had
a pair of trousers that
had big holes all over em. (The GT250)

Also distrust any electical wire that is
bolted onto aluminium (engine!). Alu-oxyde is an insulator that breaks
down
around 5 Volts, depending on the thickness
of the oxide. I had that problem with
my 6V R25 BMW. Sandpaper
all those spots.

And sorry for strangely cut-off lines in my reply.
I have an edit window the size of a postage stamp and don't know how
to enlarge it.

Rob.

 

So, basically, the battery is functioning as the voltage regulator and
once the battery is toast, the rest of the system blows itself up? The
bulbs that blew WERE black inside. This seems like it'd be horrible for
the battery.

The battery in there is completely dead so I guess that makes sense. I
just bought a voltage regulator off eBay from a DT250 so maybe that will
help things.

 

Pretty much. Actually, every load on the system was the regulator, so
once you burned out one lamp, you'd start popping everything, if what
I've heard is correct.

There's been a couple of good discussions of older 6V systems on this
group in the past, it might be worth digging into the archives and see
what tidbits show up there.

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

LED lights in combination with a switchable resistor
ought to be way more reliable than the stock bulbs.
I'd consider going that way. I especially like LED
tail lights to ensure visibility at night.

Adding a shutoff mechanism for the resistor seems like
a good idea for emergency situations where you might
be trying to conserve battery watts.

 

Those simple old dirtbikes and enduros had a "balanced" electrical
system, where the lights regulated voltage by burning up the excess
alternating current used for lighting.

The battery was in there to light the tail light, as the Japanese
required parking lights to be left on all night and American
authorities often required a tail brake light that would work for half
an hour.

The battery provided voltage stability, absorbing the excess power,
but owners wouldn't maintain their batteries and they would start
burning out all their lightbulbs.

When the headlight burned out, every other bulb would burn out quickly
if the owner revved the engine up. The parts guy at Yamaha told me
this, but I didn't believe him and I had to experience it for myself.

I remember wondering about that silly looking radial finned heat sink
and large zener diode on 1960's
British bikes. That was before I knew how zener diodes worked.

Suzuki had a tiny little voltage regulator on their TS200 around 1966.
It was a little metal cube, no bigger than one inch by one inch.

I suppose it was also a zener diode that grounded out the excess
current when voltage rose above 7 or 8 volts.

To add a zener diode to a balanced system would be as simple as
finding an 8-volt zener that could
handle about 100 watts, and hooking it to the input side of the
rectifier that charges the battery.

You wouldn't want to hook the zener directly to the battery, because
the battery would discharge through the zener if the charging voltage
ever got to the zener trigger voltage.

 

Those little 6v batteries wouldn't keep a tail light glowing for 12
hours. And the tail light, like the headlight, tended to work directly
off the flywheel. No engine, no lights.

Some old 6v dirtbikes had a proper reg/rec. My old Suzuki TS250 was one
such. About the size of a matchbox, but did the job.

 

Yes, That is what I said.

The battery acts as a 'zener' and has to swallow all
the amps that are left over.
I first noticed that on my GT250 when I cornered
and had a momentary short around the steering
column. That blew my main fuse (I did not notice that),
but I noticed a red flash, a yellow flash and a white flash right
after eachother.
Red was my tail light, (it flashed so bright that I could see it),
yellow the blinkers (I was
cornering), white was the head light. I thought someone took a picture
of me, but then realized I had no light at all. The
bike kept running.
All bulbs were black inside. I had two good bulbs
left over from the blinkers on the other side.

When I looked at the electric wiring
diagram, I could not believe my eyes and
at first thought I did not
follow the lines in the schematics correct.
Then I realized what the problem was, and also
why I sometimes had an empty battery with no juice in it,
and many times had a weak head light, and why I had to buy so many
batteries. They lasted about a year.

I still cannot figure out why they built a bike with two generators
(one idling until you switched on the light)
and no real regulator.
I still think a single generator plus regulator
is a cheaper solution.

For the electric guys among you:
the regulator was a half-bridge, only shorting
the negative pulses of the
generators, allowing the positive
pulses to always pass.
The idling generator was switched parallell to the 'normal' generator
when you switched on the light.


I swore I'd never buy another Suzuki.
And kept my promise.

Rob.

 

They don't call the Japanese "inscrutable" for nothing. ;-)

My 1960 250cc Honda Dream had alternate connections that could be
hooked up if the battery tended to go dead. What kind of engineering
leaves
the public with such a choice?

Mt GS-1100 had a 3-phase alternator with a full wave rectifier and a
shunt-type voltage regulator.

But Suzuki built wiring harnesses for motorcycles with headlight
switches and they ran one phase up to the headlight switch.

Since there was no headlight switch on US models, they installed a
short jumper wire in the plug and ran
the phase back to the rectifier regulator.

The little jumper wire got hot and wouldn't transmit that one phase
back to the RR. If you have one phase open in a 3-phase alternator, it
cuts the power output in half...

I went ahead and connected that phase to the RR unit, leaving the
fried wire in the harness.

 

That's not a bad idea... the modern ones are much better though. No one
can really sell real crap and compete these days, unless they're
American and can patent their sound and con-rod configuration.

I bought an '85 GS550EF for $200 because the rings were frozen. I put
new rings in it and had the cylinders honed. I started it up and it
started on the first crank... and started POURING thick black smoke out
the rear after about 30 seconds. After everything cooled down, I found a
huge nearly 3" diameter crater in the regulator/rectifier pack. Looked
like "phasers on KILL" for certain.

I went down to the junkyard and wired in (IIRC) a Honda 4-wire regulator
and it was fine after that.

(Historical note: this bike had weird siamesed carbs, with two throats &
slides and just one vacuum diaphragm and fuel bowl per body. I think it
was mainly space limitations. The other cool bit was you could pop the
head and block off with the engine in the frame, making replacing the
rings a walk in the park.)

I had an '82 GS1100GL that kept killing batteries, regulators, and
stators. I finally bought a new non-Suzuki regulator and stator online
instead of crap from the junkyard, installed both at the same time, and
that fixed it.

Boy, the OEM stator was crap. Crap wire. Crap soldering job. Crap
insulation on the wire. Crap connectors. Crap casting for the winding.
Crap winding job. Some kind of crap red compound slathered all over
everything. You name it, it was poorly done.

The new stator looked like something from NASA vs. something off a
Ford Pinto. And that's insulting the Pinto.

-gc

 

Oh, and another electrical "experience" I had:

One night I went around a corner on my Honda CB450SC and ALL the lights
went out, the headlight, marker lights, tail light, instrument lights.

I had to dodge a car that pulled out because he didn't see me, then my
lights came back on.

I came home, pulled the headlight out and disassembled every single
connector in there. Three of the big green/white multiconnectors were
absolutely full of water. I cleaned that out, used some water dispersant
from the big electronics supply warehouse, and never had another problem.

-gc