ISO 2 stroke ignition guru

[J-Mech]

Soooo.... this ignition system is like nothing I've ever seen on a Honda. Now, that said, I've never played with the mo-peds.

This is an A/C ignition system. It functions much differently that any other because of using A/C current.

The wire that comes to the coil from the stator is also the signal wire from the points. The points simply ground out the wire when they close, and when open, it lets the current go to the coil. (Electricity always follows the path of least resistance.) I cannot find any info on the voltage that the A/C generator puts out, but can tell you that you will not have any luck testing with a test light. My suggestion is finding out how much A/C voltage that is supplied to the coil for spark, setting the points open all the way so that they cannot close, and spin the engine and see if it is making power. Then test further from there. My guess at this point is that the winding responsible for power to the coil in the stator is bad/open. There are 3 windings in the stator. 1 for the ignition, and 2 for all other power sources. Depending on year, the voltage fed to the coil may or may not be direct fed. On some models it feeds through a silicone rectifier before going to the coil. Near as I can tell, this is just to feed extra voltage to the ignition coil, from the other two stator windings, during low voltage situations. (I.E. starting and sitting idling with all the lights on.)

I suggest you find a book or PDF of how to do a component test. I found a PDF of the supposed Honda manual for that machine, but outside of tear-down and assembly, it was vague at best.

Holler at me if I can help.

[ol'George]

The early 2 smoke single Yamaha's '68-'72 used an AC system like that.
they put out 135-150 V. to supply the ign system,-- if that helps.
look closely @ your source coil for the Ign.

[Billy-O]

Originally Posted by ford4150

There is one wire on the coil, yellow in earlier photo.
4 wires from stator. red and yellow are for lighting, black connects to yellow coil wire, green is ground.
No rectifier in the wire from the stator to the coil. There is a rectifier/regulator in the lighting circuit to keep from over-voltage the 6V light bulbs.

I do not understand. To me, the schematic clearly shows the wire from the stator intersecting the silicon rectifier on the way to coil. Care to enlighten me? There's Black/Yellow wire leading to rectifier and from rectifier it's Black/White wire that loops around the stator (in sketch) to the coil.

I thought this images without the colorful gobbygook wires might be easier to see here. Maybe/maybe not:

honda_pa50_1978_wiring_diagram_997.jpg

[J-Mech]

Originally Posted by Billy-O

I do not understand. To me, the schematic clearly shows the wire from the stator intersecting the silicon rectifier on the way to coil. Care to enlighten me? There's Black/Yellow wire leading to rectifier and from rectifier it's Black/White wire that loops around the stator (in sketch) to the coil.

I thought this images without the colorful gobbygook wires might be easier to see here. Maybe/maybe not:

Attachment 70288

In the Honda manual, there are about 25 different diagrams. Depending on what year, or model there are different diagrams. His cycle may or may not have the rectifier. Also, if you look, the ign coil is not fed off the output of the rectifier. It is fed off of one side, the voltage of that side does not go through the rectifier, so it would still be A/C voltage.

[ford4150]

"My guess at this point is that the winding responsible for power to the coil in the stator is bad/open."

I agree with this.
Since new stators are NLA and used ones on eBay are outrageously priced, without a guarantee, I'm going to convert to a CDI ignition.

Thanks to all for your time and effort.

[Terry C]

I think you would be ok with a AC brand spark plug.
Sorry couldn't resist that one

[ol'George]

Might not be too hard to use your points as a trigger, and use power from the lighting source coil (s)? to power your existing high voltage spark coil.
---or even throw in a small cigarette package size 6V. battery.
off the top of my head that seems possible.
I've done similar.
But before we condemn the ign source coil, lets see if we can do a little testing of it, gotta be a simple way to check if it has any output and/or if it is open/shorted.
I'm sorry, but I cannot get the wiring diagram on here readable or the ones on the 'net either.
I'm sure it is my lack of computer expertise.
When I enlarge them, they get as fuzzy as long haired kitten.

[Billy-O]

Originally Posted by J-Mech

In the Honda manual, there are about 25 different diagrams. Depending on what year, or model there are different diagrams. His cycle may or may not have the rectifier. Also, if you look, the ign coil is not fed off the output of the rectifier. It is fed off of one side, the voltage of that side does not go through the rectifier, so it would still be A/C voltage.

OK Jonathan, Thanks for the education. I was having trouble seeing why is there a rectifier between the AC alternator and the AC coil. Hey, you gotta pepper the know it all with questions to get answers.

[Billy-O]

Originally Posted by J-Mech

In the Honda manual, there are about 25 different diagrams. Depending on what year, or model there are different diagrams. His cycle may or may not have the rectifier. Also, if you look, the ign coil is not fed off the output of the rectifier. It is fed off of one side, the voltage of that side does not go through the rectifier, so it would still be A/C voltage.

OK Jonathan, Thanks for the education. I was having trouble seeing why is there a rectifier between the AC alternator and the AC coil. Hey, you gotta pepper the knowledgeable mechanic with questions to get answers.