250 N/C Wiring

[willyg]

The more get into the bike, the more I wonder if the motor is really a 1966. I pulled the alternator and it is a two pole/three wire type. The wires are chewed up but I think they are repairable. At least the flywheel is still magnetized. It looks like two yellow and a thick red wire come off the stator.

There is a vintage cycle swap this sunday in Long Beach, CA. I plan to attend and look for parts. Can you help me draft a shopping list of what I need to buy?

Parts I have:
-Headlight (6v 40w) rotted reflector
-Headlight switch w/key and three fuses
-Coil (condition unknown)
-Brake light switch
-Alternator (wiring needs repair)
-Points & condenser (new)
-Tail light housing & lens (no socket)
-Green warning light (no green lens)

Parts I need:
-Headlight socket
-Headlight bulb
-Red warning light (have red lens)
-Tail light socket
-Taillight bulb
-Regulator
-Wiring harness
-Dip switch (horn/kill)
-Battery

What else do I need? Should I convert to 12v? Thank you for your help and advice.

Regards,
WillyG

[DewCatTea-Bob]

" I pulled the alternator and it is a two pole/three wire type. "

____ You must mean '4-pole', as there are no "two pole" alternators... It's rotor has four magnets, correct?


" The wires are chewed up but I think they are repairable. "

____ Even so, they all should be replaced while you have the stator exposed !


" It looks like two yellow and a thick red wire come off the stator. "

____ Are you sure that one of those which appear as "yellow", is not actually just a dirty-white ?
Try scratching them both and see if one isn't more white than the other.


" Should I convert to 12v? "

____ That advice somewhat depends on which alternator you actually have.
If you're not wishing for high-powered head-lighting, then a 12-volt system could be done, in any case.


Fun-Cheers,
-Bob

[willyg]

You're right. The wires are red, white and yellow. The stator has two coils and three wires. Four poles or magnets are on the flywheel. What gauge wires should I replace with, 10 or 12? I can't tell from mine as they are very chewed, soldered, and taped. Someone has been here before.

Since I am replacing the stator wires, I may as well make my own wiring harness, as I don't have one. What gauge should I use for that? Any recommendation on connectors? I can't find anything in my manual describing wire gauge or connectors.

I have been reading through the forum about modifying they stock system. Both helpful and confusing. I just want to wire it up as simply and effectively as possible. Reliability is important. I do not plan on racing the bike. I would like to be able to ride at night and see past my fender.

Thanks for your help.

[DewCatTea-Bob]

" The wires are red, white and yellow. "

____ Then you have either the 28 or 40 watt alternator... You need to test it's circuits, to tell which.


" What gauge wires should I replace with, 10 or 12? "

____ 18ga. will work for most everything but, the headlight's wires should be 16ga.


" Since I am replacing the stator wires, I may as well make my own wiring harness, as I don't have one. What gauge should I use for that? "

____ That info can be found in another thread on this subject,
let us know if you can't find it.
Try looking-through the pair of threads titled:
"Systems to Brighten Dim Lights on Alt.Powered models" &
"Recharging 250 MK1/MK3 Magneto" ,
both currently found together near the middle of page-6, (in this topics-section of the w.site).


" I have been reading through the forum about modifying they stock system. Both helpful and confusing. "

____ Please quote any wording you find that is not clear enough for you, and I'll then gladly use other wording to simplify it better for you.


" I just want to wire it up as simply and effectively as possible. "

____ I'll be glad to direct you through that process, but first we need to determine which alt.stator you have.
What's the motor-number of your Mk3/Scrambler-engine? _ Got any pix?


Hopeful-Cheers,
-Bob

[willyg]

I posted pix under the topic of New 250 Project.

Engine #90448

I bought it as a 1966 but I don't have a title.

The headlight is a 40w unit so that makes me think it is at least a 40 watt alternator. The bike does not run so I am not sure how to test it.

I have 14 ga wire. Is that too much? I am coming from a 6v car background, as that is what I am familiar with.

There seems to be many ways to skin a cat, or wire a Duke, as it were. That is all I meant by "confusing."

Regards,
Will

[DewCatTea-Bob]

" Engine #90448
I bought it as a 1966 "

____ I've seen the pic of your DUKE which appears as a 1966-Monza, but I believe the motor is a late-1965 non-Monza model. _ Cuz for one thing, your alternator-type is not a 1966-Monza part.


" The headlight is a 40w unit so that makes me think it is at least a 40 watt alternator. "

____ Not a stock-bulb then... HL-bulb should be either 25 or 30 watts.


" The bike does not run so I am not sure how to test it. "

____ With an 'ohm-meter'... Got one?


" I have 14 ga wire. Is that too much? "

____ Unnecessarily thick ! _ But if that's what you already have lots of and wish to try to work with, then that's your call.


DUKE-Cheers,
-Bob

[willyg]

The bike probably was pieced together. Could the motor be out of a Scrambler? Is there a difference in the frame?

I do have an ohm-meter.

I will probably replace the headlight with a sealed beam anyway, as it does not work and my reflector is rotted.

Not married to the 14ga wire, it is just what I have. I don't have all the colors I need anyway. I get some 16ga and 18ga, as it is much easier to work with.

Thanks for your help, Bob.

Regards,
Will

[DewCatTea-Bob]

" Could the motor be out of a Scrambler? Is there a difference in the frame? "

____ Yes & yes...
How about some pix with the seat off, and of the motor-case where the shifter-cover fits ?


" I do have an ohm-meter. "

____ Please check the resistance between the stator-plate & each of the three wire-lead ends, (for 'short' or 'open').


" I get some 16ga and 18ga, as it is much easier to work with. "

____ Probably ought to make the 16Ga red in color.


DUKE-Cheers,
-Bob

[JimF]

To make my main wiring harnesses I use 14-gauge stranded building wire from the local hardware store. It's easily obtainable and in a good amount of different colors, and the diameter of the conductors is a good fit in conventional over-the-counter crimp-on terminals from hardware and automotive stores.

The different colors will come in handy as you run brake light, running light, horn, etc. wires into a bundle and then need to sort out the wires at the other end.

14-gauge is small enough that a loom containing several wires is not too bulky, and the individual wires are not so small that they feel flimsy or likely to break or pull out of crimped connections. The stranded 14-gauge wire is flexible enough too.

When you strip the 14-gauge wire if you knick a couple of individual strands of copper off the end you you have the extra cushion in the gauge not to sweat the reduction in current-carrying capability (ampacity.)

Building wire insulation (the jacket) is abrasion resistive, is resistive to oil, gas and grease as well as UV resistive to sunlight. Most building wire is moisture resistant too.

14-gauge is overkill with an ampacity of around 15 amps, but that provides you a safety margin for in the event of a short circuit or as I said before, if you cut off some individual strands of copper when you strip the insulation off.

In 6-volt systems resistance in the wires is more critical than in 12-volt systems, and the larger the wire gauge the less resistance is in the wire so you are doing yourself a favor there as well. Resistance in a wire causes a voltage drop along the wire. The higher the current in the wire the larger the voltage drop becomes. So the headlight wire particularly is susceptible.

Jim

[willyg]

Thanks for the info. Here is a pic of the bike with the seat off. I appreciate everyone's help.

Regards,
Will