Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

I decided to take apart the engine of my 1978 piaggio bravo and replace some bearings and I decided to take apart the magneto. Dont know why. Anyways two wires broke off. Im pretty sure the red wire connects to the red connection. I dont know where the green wire connects to. A black, green, and red wire leave the engine case. The red is for all of the lights, the black leads to the ignition coil and i think the green connects to the kill switch. my question is where does the green wire connect to on the magneto and do i have the copper coils in the right spots or do i need to switch them around

2012-07-08_00-18-47_10.jpg

Re: Rewiring a magneto

♣Slew Foot♣ /

looks like its laid out like a morini cev flywheel

the green is the brake and ignition ground.

Magneto-Wires-Chart1-591x800.jpg

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

Yea but where does the red and green wire connect to on the magneto.

Re: Rewiring a magneto

Look in the wiki....

Vespa engine rebuild has pictures....

Don't put the wires on top the coils like that they will rub against the inside of the flywheel.

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

The page helped with where everything goes but it does not have the green wire anywhere. Should I just attatch it to the closest copper coil and where on that coil?

2012-07-08_09-59-04_254.jpg
2012-07-08_10-02-28_220.jpg

Re: Rewiring a magneto

its such a pain in the ass to go look in my garage on Monday night....

the weekend, no problem

bump this question on the weekend and i have your answer

my engine is buried under Puch parts on

my workbench

Re: Rewiring a magneto

That wire needs stripped and soldered onto the little brass eyelet with the blue wire also that coil is mounted upside down.

Clean up both sides use some flux and solder it back on to the eyelet with the blue coil wire.( in same eyelet)

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

Ok i have done that already and have moved on but now i cant get spark so i replaced the condenser, points, and sparkplug. Everything is gapped right and still nothing.

Re: Rewiring a magneto

Sounds like you don't have it wired right yet.

2 black wires go to copper tab on engine bolt

red wire goes to plastic tab on side engine.

Thick wire from engine goes to tab on secondary coil other part of wire goes to kill switch.

Last wire from engine connects to the wiring harness.

Use a big rubber band to hold the spark plug on to the head when u test for spark.

Good spark looks like blue hellfire.

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

I have it wired just like that except i only have one black wire that connects to the engine other wise the other black wire is supposed to connect to the brakelight switch. And as for the last wire connecting to the wiring harness, i assume u mean the blue wire coming out of the engine and i have that going to the brake light. I dint knkw what u mean by wiring harness. Thanks for the help so far

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

The wiring is correct..... I think. I pedal and tried the brakes and they lit up and the headlight lit up but still no spark. Im probably just going to replace the ht coil and hopefully that will work.

Re: Rewiring a magneto

♣Slew Foot♣ /

you ca test the HT coil by grounding the neg side of a 6v battery to the bike frame and hitting the signal side of the coil with the positive, if its good it will spark.

it may be the missing connection for the brake signal stopping it from sparking, get your wires right before buying anything.

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

I went through the wiring twice, comparing it to diagrams. I tested the ht coil and i got a spark. I was wrong earlier when i said i had the brake light lighting up because it isnt. The wiring coming from the brakelight to the engine is right. Is it possible the ignition feeder coil could have gone bad?

Re: Rewiring a magneto

Somehow u still don't have it right.

The Primary ignition coil is grounded thru the brake light. When the brake lever is pulled it forces the ground (- + electric current) thru the brake light bulb. With brake levers un touched (not pulled) the coil goes directly to ground.

So if the bulb is burnt out the coil wont be grounded . When a brake lever is pulled the bike will stall this is so u know that the brake bulb is burnt out.

If the switches on the brake levers are messed up /broken loose it could be the problem. Each switch has 2 tiny spade connectors under the rubber boot check them. (wrong wattage brake bulb can act as if blown bulb

2 wires for spark

The blue wire from the engine to the brake wires. The other thick wire goes to the ht coil tab. this should be a double clip and have a jumper to the kill switch.

If you ground the blue wire and connect the thick wire to the ht coil u should get spark. This is called hard wire these 2 wires are all you need to get spark. as long as inside the magneto 3 wires to screw on points.

All other wires are lights : brake, tail and speedo or horn

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

I think it might b the copper igntion feeder coil because i hooked up the ignition system to the lighting coil and it started up but ran terribly

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

So i connected the lighting coil to the ignition system and the ignition coil to the the lighting system. I pedaled and it started up but there was absoltely no power. it has to be something with the ignition coil but i dont know what. The old one worked before i took it apart and i also bought a new one and that didnt work. Could it be that the new one was crap to begin with and the old went to crap by sitting around or does my moped defy physics?

Re: Rewiring a magneto

First of all I don't think the two coils on the magneto are interchangeable ie using the light coil as the primary ignition coil. I just bought new coils from mike cornell and they come in different boxes with different part numbers. One end of the light coil goes to the lights the other end,goes to ground at the magneto. The ignition coil is not grounded on either end in the magneto. One end goes to the ho coil and condensor the other end has two different destinies, either to ground via the brake bulb when that circuit is closed or I believe to ground. I will check the wiring diagram. I have pictures at home in my camera of the disassembly of my bravo magneto step by step. I can also in a bit sell you my used coils that are in pretty good shape.

Re: Rewiring a magneto

Yea , go to myrons mopeds, service, electric..and about the third diagram from the bottom is yours/ mine . Like I said there are two wires per coil, each wire has a specific path. Each of the two coils have a different ratio of inner to outrr wiring turns so don't switch them!!!!!

Re: Rewiring a magneto

ส็็็็็็็็็็็็็็็็ Joel Bruecker ส็็็็็็็็็็็็็็็็ /

I have it pretty much wired like that. My moped never had a ground coming off of the lighting coil. My old igniton coil ( i think its the ignition coil because it was hooked upto the ignition system when i took it apart) had a red wire coming out of the coil itslef which was wired into the points. It also had blue wire( Brake ground) coming off of one of the brass eyelets which was connected to the inside of the coil. so im pretty sure that it hooks upto the ignition system unless im completely wrong. I have it wired up like this

https://plus.google.com/photos/102918008620512795495/albums/5309966862442124049?banner=pwa&gpsrc=pwrd1#photos/102918008620512795495/albums/5309966862442124049?banner=pwa&gpsrc=pwrd1

( Note this is not my moped)

With what i thought was the lighting coil hooked upto the lights, the lights lit up but when i went to try the brakes the light did not light up but the bulb was good. then i hooked up what i thought the lightign coil was to the ignition system and the ignition coil to the lighting system and then the moped started but the lights did not light up.

Also when replacing the bearings i accidentally cracked the case and i jb welded it back together. could this be screwing up the ground for the ignition coil if there even should be one.

Re: Rewiring a magneto

I will look at my pics when I get home.

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