Friday, June 3, 2011

Does anyone know how to wire a headlight to a magneto?

I would wire it to a battery but the dirtbike I am trying to install the headlight on doesnt have a battery. Its a cheap 125cc honda knockoff and has a yellow, green, red, and black wire coming from the magneto.Does anyone know how to wire a headlight to a magneto?Hey Ross....



1st difficulty is wiring Color Code is NOT Universal.



You are going to have to determine which wire is what.

Easiest way,,,get yourself a cheapie multimeter aka%26gt;V-O-M from any autoparts,,Walmart,Home Depot,RadioShack,etc.

Should be under $20.



......................................?br>
IGNITION:

Points/Condensor Magnetos have ONE WIRE.

Almost Invariably a BLACK wire coming from the Mag.

It goes directly to Secondary Coil/%26quot;Spark Plug Coil%26quot;.



It often has another Black Wire %26quot;Tee'd%26quot; off of it to serve as kill switch.

Kill Switch just grounds the wire coming from the points to Kill ignition

......................................?br>
IGNITION:

CDI Magneto/Electronic Ignition usually have 2 Wires.

One for CHARGING the CDI BOX

One for TRIGGERING the CDI BOX,,,aka %26quot;ignition timing%26quot;

These 2 are almost NEVER Yellow or Green.

%26quot;Almost%26quot; is the keyword----(Just cuz I said That,,Murphy's Law will make Yours Yellow %26amp; Green,,,LOL)

......................................?br>
Determine Which are Ignition:

They are PROBABLY Red %26amp; Black.



You Should be able to see where each of your 4 wires goes.

I have a hunch the Green %26amp; Yellow go %26quot;nowhere%26quot;.



Easiest way is to make Jumper Wires---just 6%26quot; wire stripped/bare on each end.

Unplug any Connector Block,,,and connect the jumper wires.



Disconnect them One-by-One and see if engine still starts,,or has Spark @ SparkPlug.



If it requires Red/Black for example,,,for SPARK.....then Those are your Ignition wires.

Or,,whatever Color happens to allow SparkPlug Fire.



............................

The REMAINING Wires are going to be %26quot;Lighting Coil%26quot; wires.

Charging System power output.



......................................?br>
CHARGING/LIGHTING:



You'll need to test the Output of Each Wire that isn't for IGNITION.

(Probably Yellow %26amp;Green)



They produce raw A/C--Alternating Current.

NOT DC-Direct Current which is what a battery needs.



And,,they'll put out HI VOLTAGE AC Current,,,,way over 6V or 12V.



Put your Meter on 250V AC scale.

(You always start on a HIGH Scale so you dont fry your new meter-----if your Readings are LOW,,,You can then switch to a Lower Scale,,which is easier to read)



Check Each Wire Individually to Ground using the Meter's AC Scale.

(While motor is running,of course)

Rev Engine a bit to see what Max Voltage is.

It WILL be surprisingly High.,,,way more than a 6V or 12V nominal.



Find your 2 %26quot;Hi Voltage AC%26quot; wires.



......................................?br>
You will have to add a RECTIFIER.

Thats a semiconductor device which converts AC to DC.



You've got a variety of options.

**Buy an actual Motorcyle Rectifier ,,such as for a Honda 125

**Buy a Universal Bridge Rectifier--which is usually Cheaper and Better

**Build One using discreet components---simply Diodes ,,,which can be a hassle 'cuz of Sizing,,needing a heatsink,etc.

You got enough to do already instead of Building your own rectifier.



......................................?br>
Rectifiers are somewhat %26quot;UNIVERSAL%26quot;.

They have Ratings and Specs,,Sure.

But you can use a relatively HUGE rectifier,,and be so much the better.

They are rated by AMPS%26gt;%26gt;Load Capacity.

And by Voltage CAPABILITY.(NOT volt Output---ONLY how much voltage they can Stand going INTO them)

All they do is Convert AC to DC.



You can Use a 20V or 50V or 500Volt Rectifier on a 6Volt system,,for example.



But You DO need to mind AMPERAGE RATING,,,plus some sorta %26quot;safety factor%26quot;

EXAMPLE%26gt;%26gt;.a 20Amp Rectifier would do Fine on on Your Bike,,,,,,a 2Amp would be Marginal and eventually overheat %26amp; fry itself



MOST ALL %26quot;OEM%26quot; Bike Rectifiers are marginally suitable for their original applications,,,yet they last for many years.



Here's some Examples from EBAY.

Just type in the Item Number into the Search Thing.



200054074673

220101237433

330106666206

150111028330%26gt;%26gt;%26gt;350Honda,,12V Hi-Amp%26quot;Heavy Duty%26quot; for Your App



Note the WIRES in some of those pics.

The YELLOW and GREEN are INPUT from the magneto/stator/charging coil.

The RED is OUTPUT,,,,,POSITIVE (+) HOT WIRE.

The RED goes to Battery,,,or into Harness to Power the Lights.



**Important**,,,,There is a MOUNTING STUD on the %26quot;Bike-Type%26quot; Rectifiers.

You can see it clearly on Ebay #200054074673%26gt;%26gt;%26gt;the Brass-looking Screw/stud sticking out of the middle of the cooling fin plates.

That MUST be Well Grounded.

Usually it's just grounded thru being mouted to frame bracket.

Often,,and %26quot;Best%26quot; is to run an auxilliary ground wire from that stud to the engine.

If you just bolt it to a frame bracket,,,%26gt;%26gt;CLEAN THE PAINT away so Your bolting to Bare Metal.

AND%26gt;%26gt;Use your Ohmmeter setting to Check from the Mounting spot to the Engine,,,making Certain you have a Good,Solid Ground.



%26quot;Bracket bolted to frame%26gt;bolted to engine%26gt;%26gt;%26quot; is often NOT a good ground,,cuz of all the paint,etc between all the parts involved.

......................................?br>
Here's a Different kind of Rectifier,,%26quot;Universal%26quot;,,very heavy duty,,,NON-Bike.



330106950405---Sweet Deal on this set-up because it comes with about a $10 Capacitor.

The Big Cap acts like a sorta %26quot;Storage Tank%26quot; in place of a Battery.

Caps are the Heart of %26quot;Battery Eliminator%26quot; Kits.



170100422474

50Amp ,,1000Volt,,,and Tiny.



BOTH of those Type of Rectifiers function exactly same as typical %26quot;Bike Rectifier%26quot;.

The 4 Terminals on them are marked:

(-)Ground

(+)HOT



Then the Other 2 are AC IN from Magneto.

Very Simple to connect....does not matter which one goes where,,Yellow or Green .

It's AC,,Non Polar.

Yellow and Green are effectively %26quot;Same%26quot;,,

each carrying BOTH + and - as AC.

They are merely Opposite Phase.



Their symbol on Bridge Rectifiers is a ~~~~ %26quot;wave%26quot; looking symbol to represent AC

......................................?br>


On 6Volt Systems on Bikes,,,,they are UNREGULATED.

The BATTERY acts as the Voltage Regulator in an Odd way.

A Battery can only put Out it's Designed Voltage.

OVER Voltage spikes going INTO a Batt is reduced by the Batts AMPERAGE DRAW.



Not the most Precise Voltage Control,,,but it works.



When you Run a Mag-powered Light System WITHOUT a Battery,,,,,,You have NO Voltage Regulation.

Your BULBS become the Resistance.

Which they normally cannot withstand at Hi RPMS%26gt;Hi Output Voltage.



Frankly,,I'm so far outa the loop with Bikes these days,,,

I do NOT know of any 6Volt Regulator/Rectifier Assy used originally on any bikes.

Most all have always just used the Battery as their regulator.



Bike Regulators are almost All 12 Volt.

Your Mag is almost gauranteed to be Only %26quot;6 Volt%26quot;.

......................................?br>


You can either Use a Battery,,,

Or,,Use a Battery Eliminator Kit..

Or,,Use a %26quot;Home-made%26quot; Battery Eliminator---just a giant capacitor.



You MUST use a Rectifier.

You MUST use some sort of Regulator.



Here's an example of some Options of stuff that'll work from EBAY



a)

230115074371 (Just a Big Capacitor)

or,,

290101758416 (just a big capacitor)

or,,

120106111687 (way too expensive)

or,,

150110876309 (pretty expensive)



Those are all the same basic crap.

You NEED someting like any of the above,,

PLUS a RECTIFIER

Such as ;

170100422474

or,,,

220099202563

or ...

any actual Motorcycle Rectifier listed above

150111028330 is a good deal

or,,

220101237433



,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,?br>


Or,,,you can use This set-up,,,

It's got your rectifier and your %26quot;batt eliminator %26quot; capacitor all for about $12

330106950405



.........................

It ALL %26quot;hooks up%26quot; the Same.



Yellow to Rectifier,,,may be marked AC or IN or have a ~ symbol(wave)

Green,,same as above.

Dont matter which goes where.



RED FROM Rectifier to %26quot;HOT%26quot; on Batt Eliminator or + on Cap



Black or Ground or - on RECTIFIER Must be Grounded WELL.



(-) On CAPACITOR,,or - or Negative or Black on Batt Eliminator Must be Grounded Well.



Take the Power for your Lights from the RED or + ON THE CAP or BATTERY Eliminator.



The RED from your ENGINE/Magneto is most likely Ignition wire for CDI.....which is a Totally DIFFERENT deal and has NOTHING to do with Lighting.

It's a whole different kind of %26quot;red wire%26quot;.



.........................

I'm ASSUMING your bike does indeed have a Lighting Coil in the Magneto.

Those Yellow and Green wires dont normally just grow outa the aluminum.

Though it's POSSIBLE they used a %26quot;universal harness%26quot; and the Yel %26amp; Grn wires end up %26quot;nowhere%26quot; in the mag????

POSSIBLE,but not likely.



.........................

Lottsa BS to Read(and type),,,Sorry.



Step back from it all and realize it's all VERY EASY



Yellow-------Rectifier

Green-------Rectifier

Rectifier's (+) to Cap's ( +),,,then to LIGHTS

(Cap's + or BattElim's RED is same as Battery's + or RED)



Rectifier's ( -- ) to Ground

Cap's ( -- ) to Ground



MAG%26gt;Rectifier%26gt;Capacitor%26gt;Lights



Any simple switch can turn Light Off/On



SPST is mere On/Off...one wire IN ,one Out



SPDT can give Hi/Low/Off,,,,one wire IN,,,2 wires OUT to Hi/Low on Bulb.

You can find 3 position switches which have an OFF position and A or B output.



Simple Toggle switch are usually easiest to install,

Drill a hole in Headlight Shell,,,

or make a simple bracket that bolts to handlebar clamp bolts,,or whatever.



You can use crimp-on connectors,,,wire nuts,,solder the connections,,,whatever works.

Heat Shrink tubing is cheap %26amp; nice.

Electrical Tape is cheap,and works fine.

However you rig things up,,,INSULATE EVERYTHING VERY WELL.

You can mount stuff,,however you wanna,,,,,Cable Ties or make brackets??



Be careful of the Green %26amp; Yellow Wires while bike's running,,,they can knock the $#!+ out You sometimes.

So can the Capacitor or Battery Eliminator....they both STORE Electricity %26amp; can hold it for days.

Flipping the Light ON will %26quot;drain them%26quot; when bike's not running.



Oh Yeah,,,when Ya get it all rigged up,,

Start Engine and see what kinda DC VOLTAGE you get at your Red Output wire

Just check between the Cap's (+) or BattElim''s RED,,,and Ground.



Check at Idle,,,and Revved Up pretty good,,,5~6,000 RPM.

THEN decide what voltage bulbs ya need.

Probably gonna be 6Volt Bulbs.

If under about 8 Volts,,that'd be about Right

If somehow it's 9~10V or higher,,Use 12V bulbs(not likely),,,but who knows what your mag actually puts out??



Lots simpler than it sounds,,,and easy to do.



Realize the LIGHT will only work while Engine is running/mag is spinning.



If you ever WANT to,,,you can mount a Battery.

Simply connect it's (+) to the same Out Wire from Capacitor/BattElim.

And it's Ground (-),,to Ground.

The setup will also Charge the Battery as you ride along.

And lights will work off of Battery when engine's not running.



Good Luck with itDoes anyone know how to wire a headlight to a magneto?would think that red is + black is -



would also think you need some kind of regulator between the magneto %26amp; the lights...

years ago had a Bennelli 250 that had magneto...may be go to there site %26amp; see if they have a wiring Diagram that may help..........

try here

http://www.scooterhelp.com/electrics/pagDoes anyone know how to wire a headlight to a magneto?The ignition/generation system on your bike wasn't intended to run lights. It could be modified to run a headlight, but with a battery and a voltage regulator. I tried the same thing with a dirt bike I had years ago, and with no battery or regulator, the engine ran very badly with the light on.



P.S. A magneto is usually desinged with only enough electrcal output to operate the spark plug(s). So it is wired for only that purpose.Does anyone know how to wire a headlight to a magneto?you would need to add a lighting coil to the stator...not worth the hassle
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