Did I wire my external condenser right?

Was out riding trying out different jet sizes and my tomos died at WOT after about a minute. I figured I blew the condenser so I wired an external one and the bike fired up again but much weaker and will die under load. Have tested compression, cleaned carb, checked fuel flow with fresh fuel, timing, points and plug gap. Anyone out there know if I did the external condenser right?

Re: Did I wire my external condenser right?

You're 100% right that your points are arcing is a sign that your condenser is not working right.

Grounding the condenser to bare metal is the right approach.

I'm a bit confused by your wire colors. That bike sure looks like an A3 tomos, and all of the A3 wiring diagrams I can find show basically two wires coming out of the magneto: yellow for lights and black for ignition. You seem to have four: two yellow, one black, and one brown. Check out these wiring diagrams: https://www.mopedarmy.com/wiki/Tomos_wiring_diagrams

The hot lead of the condenser should only be connected to the black wire, assuming the wiring is stock.

Re: Did I wire my external condenser right?

louis borzage /

> Brian F wrote:

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

> You're 100% right that your points are arcing is a sign that your

> condenser is not working right.

>

> Grounding the condenser to bare metal is the right approach.

>

> I'm a bit confused by your wire colors. That bike sure looks like an A3

> tomos, and all of the A3 wiring diagrams I can find show basically two

> wires coming out of the magneto: yellow for lights and black for

> ignition. You seem to have four: two yellow, one black, and one brown.

> Check out these wiring diagrams:

> https://www.mopedarmy.com/wiki/Tomos_wiring_diagrams

>

> The hot lead of the condenser should only be connected to the black

> wire, assuming the wiring is stock.

Yes the engine is an a3 but the flywheel/magneto is actually off an a55. I swapped them out previously because the condenser went out on the original (go figure). There were actually 3 wires coming out from mine - yellow,black,blue. Black was coil, yellow was for the horn and the blue for the lights a believe.

Anyway, I tried the same thing with the old flywheel/magneto that I did with this one and had worse results (backfiring, most likely not timed or gapped right).

If you’re saying only the black lead should go to the condenser (on the original) then where should the other two wires going to it go? They all three need to be connected I’m sure because one is the points and the other is the magneto.

Here’s a little diagram of the original a3 setup:

0C6B2330-F333-47BC-BA61-B564A8B1550A.jpeg

Re: Did I wire my external condenser right?

Wait, how did you go about setting up an A55 stator and flywheel on the A3? The a55 has a CDI, no points, no condenser, and the trigger mounts on 2 threaded holes that are cast into the a55 cases. If you meant that you just used an A55 flywheel, I'd be surprised if that worked at all with points since I imagine that the flywheel wouldn't have an egg like shape to open the points (edited)

Re: Did I wire my external condenser right?

Wait, an A55 with points?! Are you sure about that? Tomos started using CDIs early in the A35, and all A55s came with CDI ignitions AFAIK.

But yeah, some early A35s came with points. Their wiring diagrams also show only a black wire (ignition coil / points) and a yellow wire (lighting coil). https://myronsmopeds.com/wp-content/uploads/2008/04/Tomos-Wiring-1992-93-all-Bullet-models-100dpi.jpg

I've poked around looking for a wiring diagram with the wire colors you describe but haven't found anything.

Either way I suspect something is miswired on your stator. From what I can tell the setup should be as follows:

Ignition coil: one end grounded, one end connected to points, condenser, and HT coil (black wire)

Lighting coil: one end grounded, one end connected to lighting circuit (yellow wire)

Re: Did I wire my external condenser right?

You're not running both condensors at the same time are you? (edited)

Re: Did I wire my external condenser right?

louis borzage /

> live ɘvil wrote:

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

> You're not running both condensors at the same time are you?

No I am not

> Brian F wrote:

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

> Wait, an A55 with points?! Are you sure about that? Tomos started

> using CDIs early in the A35, and all A55s came with CDI ignitions AFAIK.

>

> But yeah, some early A35s came with points. Their wiring diagrams also

> show only a black wire (ignition coil / points) and a yellow wire

> (lighting coil).

> https://myronsmopeds.com/wp-content/uploads/2008/04/Tomos-Wiring-1992-93-all-Bullet-models-100dpi.jpg

>

> I've poked around looking for a wiring diagram with the wire colors you

> describe but haven't found anything.

>

> Either way I suspect something is miswired on your stator. From what I

> can tell the setup should be as follows:

>

> Ignition coil: one end grounded, one end connected to points, condenser,

> and HT coil (black wire)

>

> Lighting coil: one end grounded, one end connected to lighting circuit

> (yellow wire)

Oh whoops, then yes I suppose it’s off an early a35 then. I’m not too familiar with these engines and the one I had looked like an a55. At any rate the flywheel/magneto combo worked just fine on my a3 before I blew the condenser on it.

I agree with what you’re saying about the way it should be wired, but my confusion arises at the point of connecting the wires to the condenser. I am stuffing three wires into one end of a connector and only one wire on the other end. I normally wouldn’t do this but I have no solder gun or better way to connect them. I suspect that is the issue, which is why I hoped someone could draw out a map for me of how to wire an external condenser.

This is the points setup currently on the bike and the diagram that is exactly how my bike is wired:

309B7B87-CAD2-46A7-9D07-D6B4F4A71AE5.jpeg
0D368EB1-C282-4075-AD45-C170F2A1D10A.png

Re: Did I wire my external condenser right?

I don't see anywhere on that diagram were 3 wires are being connected to a single wire .

Re: Did I wire my external condenser right?

tomos_condenser.PNG

You can wire the condenser to this black wire, wherever it is convenient for both wiring and grounding the case.

Condensers are typically connected close to the points to minimize inductance, but it doesn't matter much at typical moped rpms.

Re: Did I wire my external condenser right?

louis borzage /

> P D wrote:

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

> I don't see anywhere on that diagram were 3 wires are being connected to

> a single wire .

It doesn’t show on the diagram but there are three wires going into the condenser on the points backing plate. One yellow that goes to the points, one orange that goes to a coil, and one black that goes to the ignition coil.

> Brian F wrote:

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

> >

> You can wire the condenser to this black wire, wherever it is convenient

> for both wiring and grounding the case.

>

> Condensers are typically connected close to the points to minimize

> inductance, but it doesn't matter much at typical moped rpms.

If I splice the condenser in somewhere along the black wire then what do I do with the remaining two wires that where attached to the old condenser? One goes to points and the other to a coil as mentioned above. Here’s another diagram to explain my seemingly endless confusion. (Sorry and thank you):

1E556E98-3C54-4E01-900F-CB2FBED5FE3B.jpeg
2F291896-BC6B-402A-B422-7B1A1B9679E4.jpeg
76457056-BF51-441F-B363-8F072C798C3B.jpeg

Re: Did I wire my external condenser right?

Re: Did I wire my external condenser right?

I see .

You're simply switching connection points .

This is wired correctly . Maybe you have the kill wire connected later in the 'harness' .

Re: Did I wire my external condenser right?

> louis borzage wrote:

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

>

> If I splice the condenser in somewhere along the black wire then what do

> I do with the remaining two wires that where attached to the old

> condenser? One goes to points and the other to a coil as mentioned

> above. Here’s another diagram to explain my seemingly endless confusion.

> (Sorry and thank you):

Connect them together, and connect that to the HT coil. (edited)

Re: Did I wire my external condenser right?

Dirty30 Dillon /

You literally just need to place the condensor in-line between the internal coil and the HT coil.

I would just splice it in where convenient along the black where and touch nothing under the stator cover. The less overall changes you make, the less opportunity for error and easier time you will have back-tracking your mistakes.

Re: Did I wire my external condenser right?

louis borzage /

> Dirty30 Dillon wrote:

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

> You literally just need to place the condensor in-line between the

> internal coil and the HT coil.

>

> I would just splice it in where convenient along the black where and

> touch nothing under the stator cover. The less overall changes you make,

> the less opportunity for error and easier time you will have

> back-tracking your mistakes.

Yes I’m understanding that. So, since I’ve already disconnected the three wires going to the bad condenser underneath the stator cover I will go ahead and leave them all connected to each other and then find a better place along the black wire to mount the external condenser. The way I have it now I thought would work (I mean, it does, but the points arc), and I will update once I do.

Thanks all

Re: Did I wire my external condenser right?

You're overthinking it and getting a flood of confusing info. I think you've got it figured out, but let me simplify it, just in case.

Condenser wire goes to the power wire that runs to the coil. Condenser body gets grounded to the frame.

The wires going to the internal condenser stay connected. You're just removing the condenser. Think of the solder point of the condenser as a wire (like the external one has) and you're just cutting the condenser out of the circuit.

Re: Did I wire my external condenser right?

Also maybe go buy a condenser at autozone for an old chevy or something. Just look up "condenser" and pick by price or size sith a single wire. They're cheap, brand new and plenty big to do the job.

Re: Did I wire my external condenser right?

louis borzage /

Back on the road thanks to you guys! The problem was where I had connected the condenser wire to the system. I removed the three wires originally attached to the old condenser and left them connected (and tidy) inside the stator area and then connected the new external condenser to the black wire going to the coil and voila. No more arc at points and all power is back. I was definitely overthinking it - it’s been a busy couple of weeks for me.

Now that I’m rolling again my next question is what causes a condenser to malfunction? I’ve ran points on my harleys for years but never blown any, probably because I baby them. I’ve blown two (albiet old) ones, and now on my third (which is new). Is this something that mopeds just do occasionally? I imagine too many rpms or something like that would be the cause..

Thanks again for the help everyone

Re: Did I wire my external condenser right?

Yay, I'm glad you're back on the road!

Condensers are capacitors, typically of the metal film variety (high current, low ESR).

The main issue with old metal film capacitors is corrosion of the electrodes, often due to moisture intrusion. Moisture can also increase loss in the dielectric film, depending on the specific materials used.

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