Systems to Brighten Dim Lights on Alt.Powered models

[ajleone]

Here are 3 pics of what I believe is a 66-67 250 scrambler harness. This shows the power diode which is used to rectify the AC current to create a charge for the battery. ALso, just for comparision, the last pic is of a 125 Bronco headlight shell, which I believe has identical electrics to the 160 Monza Jr. The only real difference in the scrambler and bronco, is the electric horn and transformer. The diodes are cheap and readily available (TRW surplus dealers). If one were to change over higher output stator, I'm not sure these little power diodes could handle it and like Bob says, move to a "real" rectifier.

Bob - would you see an advantage in improved ignition in changin over the stator (aside from the dim light issue) ? I believe all of the NC Ducati Singles used an AC Coil and those that do have a battery, do not require it to run. Interested in your thoughts on this.

[captpaul]

Ajleone, Just for clarification,In your message to bob; you are excluding sebring,monza,mach1 correct, as n/c battery models?
Capt Paul

[DewCatTea-Bob]

_____ It was quite considerate of you to post your related pictures, ajleone !

" the last pic is of a 125 Bronco headlight shell, which I believe has identical electrics to the 160 Monza Jr. The only real difference in the scrambler and bronco, is the electric horn and transformer. "

____ While I had some experience with the Bronco model, it was not enough to cause me to memorize very much about them. _ I do know that while the electrics within the Bronco-headlight may be just about the same as that within a 160-headlight,, the electrics of the Bronco's ignition set-up are one step closer to being like that of a true 'magneto' , (compared to the OHC-models), since the ign.points are located together with the power-coils!


" Bob - would you see an advantage in improved ignition in changin over the stator (aside from the dim light issue) ? "

____ If you mean could the ign.spark be improved any enough to ignite the fuel-mix any better,, then I'd figure, no not-really.
However, the manor in which the produced power is used, can indeed have pros (& cons).


" I believe all of the NC Ducati Singles used an AC Coil and those that do have a battery, do not require it to run. "

___ Okay, first of all, there's no such thing as an 'AC-coil' ... The "AC Coil" which you may be referring to, is the 'Green-coil' which was used on all the models which did not employ battery-powered ignition.
That Green-coil makes a spark only when it is suddenly jolted with a pulse of DC type current! _ While the 'Red-coil' that's used in models which employ battery-powered ignition, requires a source of DC to first saturate the ign.coil, before a spark can then be properly produced.
__ It's actually true that even the models which use battery-powered type ignition, can indeed run their motor without battery-power -(DC-juice),, however, that's because the running -(spinning) engine is then making use of the alternator's rectified power! _ And without a battery, there's insufficient power at kicking-speed -(excessively low-RPM), to start the engine - (produce a spark) without a charged-battery connected to the system (to properly saturate the DC-ign.coil) !

____ Want any more details? _ Please just ask.


DUCATIly,
DCT-Bob

[kmev]

So before I make any suggestions, I'd like to know how comfortable you are with screwing-around with the various soldering-connections? _ As you could choose to do some elaborate modifications and end-up with a relatively complex system (as I've always chosen to do for myself).
Sticking with the simplest ("4 wire") modification, will only require for that 'ground' of that one coil-lead (from the darker power-coil), to be un-soldered & connected to a 4th wire-lead.
__ Please let me know what you're now thinking.

I am more than comfortable rewiring the stator, but I think simple is better, so I would like to go with the 4-wire, 6 volt system.

So where will this fourth wire go after I connect it to the stator?

Keith

[DewCatTea-Bob]

" So where will this fourth wire go after I connect it to the stator? "

____ Okay Keith, after you've un-soldered and completely isolated that (currently grounded) coil-lead from ground, and, connected that particular coil/winding-lead to an 18ga-wire -(preferably of extra-finely stranded copper or silver),, then that new/4th-wire should run, (along with the white & red wires), up to the plate that's welded to the frame's back-bone. _ And there the 4th-wire will need to be (electrically & physically) connected to one of the two AC-inputs of a full-wave rectifier -(FW-rect./bridge-block) that's rated to handle at least 6-amps & 50rms-volts. - (NOTE, such a 'FW-Bridge'-block that just meets these minimum-requirements, may actually cost more than the more popular such unit which is rated at 25amps & 200 Peak-Inverse-voltage, (and is "block" shaped @ 1" x 1" x 1/2" thick with a 1/4" mounting-hole through it's center, and also comes with handy spade-connector terminals, often found for under just 3-bucks!)
__ The other AC-input of your FW-rect.block will be electrically connected to either the WHITE or the RED wire-lead (depending on your chosen wiring setup).


GoodCheers,
DCT-Bob

[ajleone]

Bob,
Great info on the different between the coils - what you say makes sense now that I think about it.

So, here's another question: Does a battery system versus a non-battery system, offer any difference in (a) starting effort or (b) ignition run-time reliability ?

Thanks !
Tony

[kmev]

...the 4th-wire will need to be (electrically & physically) connected to one of the two AC-inputs of a full-wave rectifier...the other AC-input of your FW-rect.block will be electrically connected to either the WHITE or the RED wire-lead (depending on your chosen wiring setup).

On the motorcycles I'm familiar with all the stator wires run to the regulator, one wire runs from the regulator to the battery, and the battery then powers the entire electrical system. This is obviously different, so I'm going to require a bit more hand-holding, especially since this bike came with no wiring harness, whatsoever.

So two of the wires go to the rectifier - the "4th" wire and either the white or red. How do I choose which other wire, and where do the remaining two wires go?

[DewCatTea-Bob]

" Does a battery system versus a non-battery system, offer any difference in (a) starting effort or (b) ignition run-time reliability ? "

____ Yes! ... With a battery-powered ignition-system, (if the battery has a good charge), the motor doesn't need to be kicked-thru fast, in order to have a good ign.spark produced! _ Thus a lazier kick on the starter-lever can start a warmed-up motor.
__ While the alternator-powered ign.system requires the engine to have a fairly-decent spin put into it in order to have a spark produced (that's just as good).
(Not to mention that the battery-powered system isn't as likely to cause a KICK-BACK! - [Due to the difference between the ignition advancer-units.].)
____ You'll have to explain to me better, what you actually mean by "ignition run-time reliability" .

Tillater,
-Bob

[DewCatTea-Bob]

By kmev: ...
" So two of the wires go to the rectifier - the "4th" wire and either the white or red. How do I choose which other wire, and where do the remaining two wires go "

____ I had already intended to tell you more wiring-info, and I'll gladly continue-on & see you thru your entire electrical-system redo-job, cuz rewiring DUKEs is my favorite thing to do with them!
__ The simplest way,, would be to also directly connect the RED-wirelead, (to complete the source of AC to the pair of AC-inputs on the FW-rect.block), and, directly connect the positive-output of the FW-rect.block to the positive-post of the battery, as well as connect the FW-rect.block's negative-output directly to ground.
However, the simplest-way is not the smartest-way! ...
__ For one thing, any rectifier will eventually run the battery down! _ So a key-switch should be used to break the circuit (conveniently when the rest of the electrical-system is shut-down.) _ (Most such ign.switches are capable of doing the job,, like the wide-case key-switch, which has 3-terminals.)
So for this less simple route, the positive-output of the FW-rect.block would go to be connected to the ign.switch.
__ Now if the lights are to be left turned-on at all times, then leaving the Red-wirelead permanently connected to the FW-rect.block, would be the simple way to go. _ But if the lights are turned-off for a long time while riding at higher RPMs, then you'd need a voltage-regulator, (especially with smaller batteries). _ And many voltage-regulators can cause the alt.power-coil to overheat, and also cause engine to use more fuel than otherwise necessary!
So for times when the lights are off, the weaker output of the WHITE-wire could be left connected to feed it's trickle-juice like power into the system to keep the battery supplied,, and when the lights are on, a switch could be used to allow the relatively high-output available from the RED-wire to feed the system (and thus keep the battery from getting drained by the lights). _ (The Japanese systems incorporate such a switch for just that very purpose, built right into the light-switch!)
Now doesn't that seem like the smart way to go?

____ I'm ready for more questions... Even if you don't think you have any, it would still be a good idea to ask if I have any advice before you choose to complete any step in your wiring-job.

____ By the way Keith, can you tell me which wire-lead (yellow or red) that your ignition-coil was wired-up to, when you first got that Scrambler of yours? - (I have reason to think that it was not wired correctly before.)


Good-Cheers,
DCT-Bob

[kmev]

I'm ready for more questions... Even if you don't think you have any, it would still be a good idea to ask if I have any advice before you choose to complete any step in your wiring-job.

____ By the way Keith, can you tell me which wire-lead (yellow or red) that your ignition-coil was wired-up to, when you first got that Scrambler of yours? - (I have reason to think that it was not wired correctly before.)

Oh, I've got plenty of questions....

First, as I received the bike, the yellow wire was connected to the coil. It ran, but not well. Of course, the poor running could have been due to the 100 other problems the bike had.

Below is a diagram of my current thoughts on a wiring harness - this is far easier than trying to describe it, and hopefully it is immediately obvious where I am having problems, where I am wrong, and what components I am planning to include.

Wisconsin has a headlight law and I will never be running at high RPMs without a headlight, so a regulator should not be necessary (as you described above). At this point I am planning to have the high beam hard-wired without a dimmer switch, but this could be easily added at a later time should I choose to have one. I think it makes sense to be able to start and run the bike with the lights off and only turn them on as I get underway, and this should be easily handled by a 3-way ignition/light switch.

My outstanding questions at this point are how to wire in the battery, which may or may not answer the question of where to route the white and yellow stator wires.

Also, the OEM specs called for a 6 volt, 7 Ah battery. Is this still the appropriate choice? And, can I wire the Sebring headlight switch to serve as the 3-way switch? I looked it over tonight and I was not immediately obvious if I could.

I do have all the different wiring diagrams from the service manual to reference. Looking at the early SCR/Mark 3 diagram, however, I cannot determine how one kills the motor. I do not see a ground or any type of switch between the stator and the spark plug. How did one kill the motor on these models?

And, if there are grave errors in my reasoning please point them out.

Thanks,
Keith