spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Bob Blarney /

Aug 20, 2019 10:21AM

Thanks for your attention.

I'm sorting a basketcase NC50, and when I did the electrical checks, I found no continuity in the rectifier and the spark plug coil cable (the black/white wire test worked).

When I checked the continuity of the alternator wires, there is continuity through the black/white wire but not through the yellow or white wires. Do I conclude that the alternator is toast?

I also noted in the shop manual to never turn the flywheel clockwise. If that was done, would it have burned out the components?

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

live ɘvil /

themotorhead

Aug 20, 2019 11:56AM

> Bob Blarney Wrote:

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

> Thanks for your attention.

>

> I'm sorting a basketcase NC50, and when I did the electrical checks, I

> found no continuity in the rectifier and the spark plug coil cable (the

> black/white wire test worked).

>

> When I checked the continuity of the alternator wires, there is

> continuity through the black/white wire but not through the yellow or

> white wires. Do I conclude that the alternator is toast?

>

> I also noted in the shop manual to never turn the flywheel clockwise.

> If that was done, would it have burned out the components?

Nope, it has to do with wind up starting mechanism on oppisite side of motor being damaged. (edited)

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Bob Blarney /

bob_blarney

Aug 20, 2019 01:25PM

> live ɘvil Wrote:

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

> > Bob Blarney Wrote:

>

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

>

> > Thanks for your attention.

>

> >

>

> > I'm sorting a basketcase NC50, and when I did the electrical checks, I

>

> > found no continuity in the rectifier and the spark plug coil cable

> (the

>

> > black/white wire test worked).

>

> >

>

> > When I checked the continuity of the alternator wires, there is

>

> > continuity through the black/white wire but not through the yellow or

>

> > white wires. Do I conclude that the alternator is toast?

>

> >

>

> > I also noted in the shop manual to never turn the flywheel clockwise.

>

> > If that was done, would it have burned out the components?

>

> Nope, it has to do with wind up starting mechanism on oppisite side of

> motor being damaged.

Can you tell me more? I replaced the cover with all of the starter mechanism, and it winds up and releases the crankshaft as it should. Besides that, there are no electrical components in the starter/transmission assembly. Is it a matter of installing at a particular phase in the 2-stroke cycle?

In the schematic shown in the shop manual, the yellow wire is attached to the lighting circuit (which doesn't care whether it's AC and DC current powering the head and tail lights), and the white wire goes to the rectifier, which I expect charges the battery by blocking the negative-going portion of the AC waveform.

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

live ɘvil /

themotorhead

Aug 20, 2019 01:39PM

Do not turn motor backwards because of wind up starting mechanism. HAS NOTHING TO DO WITH ANY ELECTRIONICS.

If you do inadvertently turn it backwards then all that is needed is to pull rear brake lever to release spring.

What happens is that if its turned backwards it winds the clock spring some. Then when one goes to start motor by winding clock spring with pedal it gets over wound and breaks or fails

Try it and you will hear the ratchet paws on the starter side clicking as it winds up the starter spring. Just be sure to pull rear brake lever to release before you go to start motor. (edited)

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Bob Blarney /

bob_blarney

Aug 20, 2019 02:44PM

> live ɘvil Wrote:

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

> Do not turn motor backwards because of wind up starting mechanism. HAS

> NOTHING TO DO WITH ANY ELECTRIONICS.

>

> If you do inadvertently turn it backwards then all that is needed is to

> pull rear brake lever to release spring.

>

> What happens is that if its turned backwards it winds the clock spring

> some. Then when one goes to start motor by winding clock spring with

> pedal it gets over wound and breaks or fails

>

> Try it and you will hear the ratchet paws on the starter side clicking

> as it winds up the starter spring. Just be sure to pull rear brake lever

> to release before you go to start motor.

Your comments have no relevance to the problem. The starter system works perfectly.

The problem is in the electrical generation system. The important point is that the shop manual warns that rotating the crankshaft in the 'wrong' direction may somehow damage the generator - the ignition and the lighting and battery charging circuit components.

I'm wondering if, during the installation of starter crankcase, that the generator flywheel was rotated in the clockwise direction, and so damaged the electrical system.

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Nick Haber /

khool1499

Aug 20, 2019 03:30PM

> Bob Blarney Wrote:

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

> Your comments have no relevance to the problem. The starter system

> works perfectly.

>

> The problem is in the electrical generation system. The important point

> is that the shop manual warns that rotating the crankshaft in the

> 'wrong' direction may somehow damage the generator - the ignition and

> the lighting and battery charging circuit components.

>

> I'm wondering if, during the installation of starter crankcase, that the

> generator flywheel was rotated in the clockwise direction, and so

> damaged the electrical system.

Are you trying to troll? Read what has been said again; the shop manual warns that not to protect the electrical system but to protect the starter mechanism. Wind that shit backward then go to start it and you'll see what he means cause your starter spring will break.

He's saying your electrical issue has nothing to do with the flywheel being rotated the wrong direction. From an electronics standpoint, that doesn't really make sense. Nothing has been damaged from magnets spinning the opposite rotation of normal operation (edited)

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

live ɘvil /

themotorhead

Aug 20, 2019 04:19PM

> Bob Blarney Wrote:

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

> I also noted in the shop manual to never turn the flywheel clockwise.

> If that was done, would it have burned out the components?

NO NO NO NO NO!

I answered your question and did so with the correct reason.^^^

Maybe mopeds are not for you. (edited)

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Bob Blarney /

bob_blarney

Aug 20, 2019 04:53PM

> Nick Haber Wrote:

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

> > Bob Blarney Wrote:

>

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

>

> > Your comments have no relevance to the problem. The starter system

>

> > works perfectly.

>

> >

>

> > The problem is in the electrical generation system. The important

> point

>

> > is that the shop manual warns that rotating the crankshaft in the

>

> > 'wrong' direction may somehow damage the generator - the ignition and

>

> > the lighting and battery charging circuit components.

>

> >

>

> > I'm wondering if, during the installation of starter crankcase, that

> the

>

> > generator flywheel was rotated in the clockwise direction, and so

>

> > damaged the electrical system.

>

> Are you trying to troll? Read what has been said again; the shop manual

> warns that not to protect the electrical system but to protect the

> starter mechanism. Wind that shit backward then go to start it and

> you'll see what he means cause your starter spring will break.

>

> He's saying your electrical issue has nothing to do with the flywheel

> being rotated the wrong direction. From an electronics standpoint, that

> doesn't really make sense. Nothing has been damaged from magnets

> spinning the opposite rotation of normal operation

I think you misunderstand something.

I don't know if the previous owner spun the engine backwards when the starter case and mechanism was removed from the engine.

The engine was not spun backwards while the starter mechanism was installed and in place. It is not damaged in any way. The flywheel was only jiggled when I re-engaged the pawls on the starter sprocket.

For that matter, I'm inclined to think that spinning the crankshaft by hand (when the starter case & mechanism is removed) should not have any effect on the electrical system or the mechanical systems. But it is stated specifically as a warning in the shop manual, on page 12-1 (see attached image) "Never turn flywheel clockwise during disassembly or reassembly."

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Jack Rutherford /

churioz

Aug 20, 2019 05:08PM

"I also noted in the shop manual to never turn the flywheel clockwise. If that was done, would it have burned out the components?"

No

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

live ɘvil /

themotorhead

Aug 20, 2019 05:10PM

> Bob Blarney Wrote:

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

> > Nick Haber Wrote:

>

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

>

> > > Bob Blarney Wrote:

>

> >

>

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

>

> >

>

> > > Your comments have no relevance to the problem. The starter system

>

> >

>

> > > works perfectly.

>

> >

>

> > >

>

> >

>

> > > The problem is in the electrical generation system. The important

>

> > point

>

> >

>

> > > is that the shop manual warns that rotating the crankshaft in the

>

> >

>

> > > 'wrong' direction may somehow damage the generator - the ignition

> and

>

> >

>

> > > the lighting and battery charging circuit components.

>

> >

>

> > >

>

> >

>

> > > I'm wondering if, during the installation of starter crankcase, that

>

> > the

>

> >

>

> > > generator flywheel was rotated in the clockwise direction, and so

>

> >

>

> > > damaged the electrical system.

>

> >

>

> > Are you trying to troll? Read what has been said again; the shop

> manual

>

> > warns that not to protect the electrical system but to protect the

>

> > starter mechanism. Wind that shit backward then go to start it and

>

> > you'll see what he means cause your starter spring will break.

>

> >

>

> > He's saying your electrical issue has nothing to do with the flywheel

>

> > being rotated the wrong direction. From an electronics standpoint,

> that

>

> > doesn't really make sense. Nothing has been damaged from magnets

>

> > spinning the opposite rotation of normal operation

>

> I think you misunderstand something.

>

> I don't know if the previous owner spun the engine backwards when the

> e starter case and mechanism was removed from the engine.

>

> The engine was not spun backwards while the starter mechanism was

> installed and in place. It is not damaged in any way. The flywheel was

> only jiggled when I re-engaged the pawls on the starter sprocket.

>

> For that matter, I'm inclined to think that spinning the crankshaft by

> hand (when the starter case & mechanism is removed) should not have any

> effect on the electrical system or the mechanical systems. But it is

> stated specifically as a warning in the shop manual, on page 12-1 (see

> attached image) "Never turn flywheel clockwise during disassembly or

> reassembly."

Let me know when you get to this point in your rebuild.

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Bob Blarney /

bob_blarney

Aug 20, 2019 06:13PM

Ah, I think I understand the purpose of the warning in the shop manual. It's a safety issue.

If you think about it, turning the flywheel clockwise from the alternator (right) side is actually the same direction that starts the engine, i.e. counterclockwise as viewed from the pedal starter (left) side of the bike.

Although it is not stated, there may be a (remote?) possibility that rotating the flywheel clockwise (facing the alternator (right) side of the bike) might result in an unintended starting of the engine, which could be dangerous.

i think the problems in the electrical system are unrelated to the turning of the flywheel. Perhaps the previous owner connected the battery backwards, and possibly started the engine too.

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Aaron Blair /

aaronb

Aug 21, 2019 04:52AM

Did you clean the points? Are the points opening? Are those two wires without continuity going to the points?if so it's normal. Because the points are open at that time. Spinner until you have continuity.

Measure the resistance on both sides of the ht coil(it's a transformer). The whole "alternator" as you called it can't be toast, worse case scenario your ignition coil is shorted. In which case you pull the flywheel and replace it.

Wait, does the express have a cdi? If so,lol disregard. (edited)

Re: spinning the NC50 alternator clockwise kills it, and the rectifier & coil?

Bob Blarney /

bob_blarney

Aug 21, 2019 07:41AM

Aaron, no, there is no CDI.

The alternator provides current for three functions, with three separate coil windings (see shopmanual image):

1. Ignition (blk/wh wire) leading to the ignition condenser & coil under the seat.

2. Lights (yellow wire) leading to the light switch on the left handlebar.

3. Battery charging (white wire) via the rectifier diode under the seat.

There is no continuity to ground through the yellow and white wires within the alternator, and the ohmmeter reads infinite resistance for both wires.

There is continuity to ground through the ignition circuit within the alternator, but it could be that the points are closed but the coil winding is open too.

I think it's time to remove and examine it, and probably replace it.

MOPED ARMY

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