Starter switch on 67 Scrambler

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DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

Re: Starter switch on 67 Scrambler

Postby DewCatTea-Bob » Fri Mar 20, 2015 10:06 am

[quote= Adam ...
" After reviewing, the previous owner pretty much had the same idea; one wire connected at the HT Coil. "

____ Not clear... You mean one green-wire ?
If so, that's not abnormal and actually same as stock.



" Connection must have been bad.

____ It wouldn't matter if the green-wire's connection to the ign.coil was bad, as the ignition would then still fire (just as if the key-switch was in it's 'ON' / ungrounded position) !
(It seems you still haven't properly grasped the actual manor in which the key-switch/ign.circuit is actually able to turn-off the ign.system.)
__ If the green-wire connection between the ign.coil & k.switch had been bad,, then all that would cause, is the k.switch would then not be able to turn-OFF the ignition !



" There is actually no 2nd green wire going to the key switch. "

____ Then that means we're pretty-much back to the same circuit-scheme that I had originally assumed the wiring-system was arranged as (with the single green-wire at the key-switch), after-all.
__ And without the primary green-wire (from the yellow/power-wire to the k.switch-terminal), there's then NO mag.power to be returned-back onward to the ign.coil (through the remaining green-wire) ! _ Thus-then no ign.spark !
(And again, if any part of that ground-line circuit to & through the k.switch was faulty,, the worse that could result from such, is that the ign.system couldn't be turned-OFF !)



Also, the black wire going from the coil to the points system
was crudely twisted together and taped up. This was in bad shape (rusted) and replaced by me at the time I worked on the green wire.


____ That's indeed a possible trouble-source for no ign.spark ! _ However no wire-connection between the yellow/power-wire and the ign.coil is certainly a DEFINITE trouble-source !
__ Still even-so however,, you should've checked for ign.spark right-after EVERY little such change you made, so that you'd know exactly what actually made the successful-difference.




perhaps you (elaborately) pulled-out the missing green-wire from out-of the headlamp-harness and-then rather directly-connected -('rerouted') it straight-to the ign.coil ?
I guess that could explain your posted specific scheme-changes indicated for your altered green circuit-pathway,, AND-also, likely explain why your key-switch pictures don't include showing the missing green-wire !?

" ****I X'd that out for my purposes. While tracing the wires
I assumed the 2nd green wire was in there somewhere so to avoid confusion later, I indicated that it is currently not being used. After reviewing it again recently, it looks like it is only one wire that is joined by a connector at the coil post.
"

____ Okay then,, I now gather that the engine didn't run due-to lack of ign.spark before you ever got your hands on it, in the first-place.
So now it's finally become rather apparent that it actually was someone-else who had endeavored to screw-around with the green-wire circuit, and evidently never straightened-out whatever they were meaning to get accomplished.



" I had replace this with a fresh wire from the block to the coil. "

____ Okay then,, my assumed-guesswork that you had pulled-out the primary green-wire (from going-to the k.switch-terminal), and 'rerouted' it rather directly to the ign.coil, actually was-not the particular correct assumption,, as you had actually rather used another -(utility-piece) wire-length to essentially jump the yellow-power/wire directly-to the ign.coil, (and-thus before, only meant that you had merely 'rerouted' the green electrical-circuit rather than the physical green-wire ITSELF).
__ It's nice to finally have that all straightened-out ! 8-)




Adam wrote:Once the switch was removed from the equation, I got spark right away
DCT-Bob wrote:__ I'm thinking that it really wasn't actually the removal of the key-switch from the circuitry that seemingly changed your results, but rather that the magneto-power of the yellow/green-circuit wasn't properly getting normally circuited up-to the k.switch in the first-place (so that the mag.power could then continue-onward back-to the ign.coil) !

****You might be right in this aspect. I didn't change one thing at a time during this process to pinpoint the issue, "

____ Well, with you now having the missing primary green-wire's connection-function finally substituted (with your "fresh" jumper-wire),, all you'd have to do to prove whether my deduction is actually correct, is to reconnect the secondary green-wire (between the ign-coil & k.switch), and see that there's then ign.spark still available, (with the key inserted of-course) !
And-also, with your jumper-wire removed,, you should then find your ignition-issue to be once-again back at it's 'square-one' aspect-level too, as well !




So I suggest that you merely just retain your jumper-wire/connection between the yellow/power-wire & ign.coil, (and-also of-course continue with the stock employment of the single green-wire/circuit from the ign.coil to the [properly grounded] k.switch ground-circuit.

" ****I will give it a try this weekend and add the result to this post. "

____ Okay, good !
__ And after you've then found that your entire ignition-issue is solved,, I strongly-suggest that since your primary green-wire is missing, you really ought replace your temp.jumper-wire with a rather permanent YELLOW-colored wire to connect the yellow/power-wire (from the terminal-block) to the ign.coil's POINTS-terminal !
And of-course at that same coil-terminal, include attachment of the (now lonely) green-wire to the k.switch,, so that your ign.power can still remain keyed ON & OFF (by letting the k.switch defaultly GROUND-out the mag.power [whenever the key is out]) !


Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

Adam
Posts: 29
Joined: Thu Oct 30, 2014 12:02 am

Re: Starter switch on 67 Scrambler

Postby Adam » Mon Mar 23, 2015 8:57 pm

So over the weekend, I ran the other wire (yellow instead of green) from the block to the key switch. Then reconnected the green wire from the same terminal on the key switch to the HT coil. I was able to verify spark when the key was IN and no spark with the key OUT. Couldn't get it started this time though but that is (possibly) another topic. Thank you for all of your help.

-Adam

DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

Re: Starter switch on 67 Scrambler

Postby DewCatTea-Bob » Tue Mar 24, 2015 7:57 am

[quote= Adam ...
" I ran the other wire (yellow instead of green) from the block to the key switch. Then reconnected the green wire from the same terminal on the key switch to the HT coil. "

____ That power/kill key-switch wiring-circuit is exactly as the stock circuit-pathway originally intended by Ducati, and of-course should function just as you've found !
However it's somewhat of a waste to detour the mag.power-juice through all the extra wiring-length up into the headlamp and back to the ign.coil (when the required power-juice circuit-pathway could rather be left merely with the shortcut-pathway as that of your temporary/test jump-wire [from yellow/block-terminal to ign.coil]) !



" I was able to verify spark when the key was IN and no spark with the key OUT. "

____ Of-course that's just as expected now. _ But is it your wiring-circuit from the yellow/block-terminal to the k.switch that's actually bottom-line responsible for that result and change with your ign.function status ?
It seems we're still left with the mystery of whether your Duke fell into your hands (from another owner) in the condition of not-running due-to the (supposedly) missing primary green-wire (normally connecting the yellow/block-terminal to the k.switch) !?
What's your-own conclusion as to exactly what was the original main-problem in the very first-place (when you first discovered the lack of ign.spark) ?



" Couldn't get it started this time though "

____ Did you then (at that time) think to also try comparing that wiring-change you've recently completed, against/with your previously successfully-used jumper/hot-wiring shortcut-circuit, (to discover if whether there was any difference in getting started-up) ?
Cuz it may possibly be that the longer/detour circuit-pathway offers just-enough extra resistance to reduce spark-intensity just enough to make the difference, (although in that-case, that would tend to indicate another shortcoming somewhere).


Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob


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