Re: Point gap vs timing

Now you know why there's an extra .010 size in brass (non-magnetic). (edited)

brass.jpg

Re: Point gap vs timing

> Scott Bard Wrote:

> -------------------------------------------------------

> Another piece of the puzzle to add into the whole “ spark output “

> circuit is the “air gap” of the stator coils to the magneto.

>

> I bought a barn find 1979 Puch maxi with a ZA50 engine.

>

> The magneto was removed from the moped when I bought it.

>

> I was chasing a no spark condition.

>

> Followed the normal troubleshooting steps of cleaning and setting

> points.

>

> As it turns out, there was no air gap of the coils to the magneto.

>

> From what I found, the coils need to be .020 away from magneto to

> generate output.

>

> So now that there is the air gap to the coils, I have spark and output

> for the lights.

>

> I suspect the previous owner at some point, had the magneto off and used

> a flat blade screwdriver to loosen every flat blade screw behind the

> magneto.

>

> A Girl Scout cookie box lid, the green o es with the mint cookies, is

> .020 thick.

I'm sorry. It's not clear where your 'air gap' is located. The magnets are glued to the spinning flywheel. The coils are wound on iron cores (laminated silicon steel, actually) and are bolted to a mounting plate so they stay just inside the flywheel rim. If there wasn't an air gap between the magnets and the coil cores the flywheel (and the engine) couldn't rotate: the magnets would scrape the coils. When there is a small gap between coils and magnets (about 20 thousandths of an inch is a good distance) those magnets zoom past the coil cores, and that generates electricity for ignition and lights. That whole assembly, flywheel, magnets, coil, and all, is generally known as the 'magneto.'

Can you clarify what it was you did to get your bike working?

Mark Kinsler

Re: Point gap vs timing

Look! A peacock!

Re: Point gap vs timing

Nothing to do with mopeds, but:

The guys who build our giant steam-powered electric generators worry about air gaps a lot. Parts expand as they heat up. And even if you compensate for that, air gets pulled along by the rotor and gets ram-compressed in the air gap, which causes even more heat where you don't want it. So besides having a huge fan inside the generator case, they fill the thing with the world's slipperiest gas, which is hydrogen. That also prevents oxidation of the electrical insulation in there.

M Kinsler

Re: Point gap vs timing

Friendly tip- Flat View is easier on this forum than threaded view :)

The coils are indeed mounted to the stator plate, but adjustment is possible (at least on Puchs) so that the coils can be pushed out or pulled in enough to change the air gap. Hence the "what is this sound coming from my magneto" posts on here every now and then (coil rubbing.)

Re: Point gap vs timing

Dirty30 Dillon /

^^^ The coils have tolerances built into them to allow gapping the coils to the flywheel

Re: Point gap vs timing

> Den 23 Wrote:

> -------------------------------------------------------

> Now you know why there's an extra .010 size in brass (non-magnetic).

A single brass blade is included in some feeler gauge sets. This is because early models of electronic ignition systems had a requirement that the air gap between the reluctor and the pickup had to be set with a non-ferrous metal (any metal that does not contain iron)

So that wouldn't apply to an "analog" points type ignition.

Re: Point gap vs timing

Richard Eberline /

Bosch, the manufacture of the coils has the air gap at .006 to .008. Converted from the metric measurement.

Re: Point gap vs timing

> Richard Eberline Wrote:

> -------------------------------------------------------

> Bosch, the manufacture of the coils has the air gap at .006 to .008.

> Converted from the metric measurement.

And thats why I own metric feeler gauges. Forgo the conversion and have a more precise measurement on metric applications. Fractional inch does not equate to an exact metric size, so you are stuck using whatever's closest.

Re: Point gap vs timing

Mark,

To clarify, the air gap I mentioned was the distance between the magneto and the coils.

Earlier, I mic’d out a Girl Scout cookie box lid when I needed something thin.

The box thickness is .020.

708647DE-8F57-498E-8FBC-0A4557B46982.jpeg

Re: Point gap vs timing

On a Puch ZA50 engine, the coils can Be adjusted closer or farther from the inside of the magneto.

A6FA6CFC-725D-4D94-A96F-792DBCBC41C0.jpeg

Re: Point gap vs timing

A6FA6CFC-725D-4D94-A96F-792DBCBC41C0.jpeg

On a Puch ZA50 engine, the coils can Be adjusted closer or farther from the inside of the magneto.

Re: Point gap vs timing

It sure looks like all these magnetos are essentially identical, plus or minus an extra coil. Are all the condensers and points the same? And is there an electronic ignition system that'll replace these?

Mark Kinsler

Re: Point gap vs timing

Dirty30 Dillon /

Magnetos and flyweights are different across brands, as are the point set and condensor.

It's worth moving the condensor outside the flywheel anyways

Re: Point gap vs timing

I've used external condenser when testing the existing one, but aside from strange home-made electronic alternatives--I think an SCR activated by a Hall-effect device, maybe--there's not much to be done about the ignition points except to replace them.

I thought I saw some sort of electronic ignition at Myron's Mopeds or somewhere.

Mark Kinsler

Re: Point gap vs timing

> Scott Bard Wrote:

> -------------------------------------------------------

> To clarify, the air gap I mentioned was the distance between the magneto

> and the coils.

To clarify , this complete unit ( everything in the illustration below ) is a magneto . Not just the flywheel .

Re: Point gap vs timing

Dirty30 Dillon /

The are electronic ignitions for most makes of moped. You haven't mentioned which one you have.

Re: Point gap vs timing

Mine is a 1984 Trac Clipper, which is essentially a no-battery Korean Batavus. There's a two-coil Bosch magneto. Someone has something for this?

Mark Kinsler

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