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 Post subject: Re: Replacement coils...
PostPosted: Wed Jun 15, 2016 3:34 pm 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 235
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
"what I don`t understand is that you said in your first post the dropped cylinder followed the bad coil, hence the horizontal cylinder worked when the coils were swapped, right? Now there`s no spark on that cylinder no matter what CDI or coil you use. Hmm..."

I think I can explain how I first thought to test for a bad coil (it was dumb and is embarrassing): I believe what I did was simply swap out the negative wire of each coil in pure ignorance thinking that would do the trick. But this was days ago and I have kind of a poor short term memory.

The first time the horizontal cylinder dropped out, it did so for just a second and fired again. Twice in short time as I was on the SF Bay Bridge after a rare cappuccino at Cafe Trieste (US$4.25!) in North Beach. The second time was a day later (for good it seems) as I was on the freeway heading toward Mt. Diablo.


"If it is an intermittent wiring issue between pick ups and CDI units it would have been a coincidence that it worked the first time you tried"

I really thank you all for your guidance and assistance. I will use the ohm meter to check continuity of the neg wire off the horizontal coil to the CDI unit. Those particular wires are the least trustworthy on my Paso: they are cloth insulated and seem like there is some play in their wire to terminal connections even though I've tugged on them. These cloth insulated wires are shrouded by wiring harness insulation throughout their run to the coils. I can imagine a short or break in the one of concern. I do not seem to have any grease, grime, moisture, oxidation or rust that is visible on any terminals, exposed wire or ground connections. Fortunately, this Paso seems to have been coddled indoors during its lifetime. The majority of its life was under the care of a jet airline pilot, any subsequent owners have at least garaged her.

I will certainly execute the coil wiring modification. Finally. I'll take all of your advice and check the continuity between the pick-up and the coil and analyze the existing condition as it passes through the grommet at the engine case. I'll press and pull some more to the wiring inside the harness insulation just above the grommet and also by the horizontal cylinder's CDI unit. Thank you all so much.


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 Post subject: Re: Replacement coils...
PostPosted: Wed Jul 13, 2016 6:47 am 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 235
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Just an update: Turns out the issue was a bad pick-up. I took the bike to Nichols Manufacturing (Ducati specialists) in Milpitas CA this morning and told Mike (Service Manager Extraordinaire) what I had done so far. Mike used his ohm meter to check continuity of the neg wire off the horizontal coil to the CDI unit and found no resistance (an open circuit). This was all he needed to diagnose the bad pick-up. To my amazement he keeps aftermarket replacements in stock. He showed one to me. He will now just open her up, clip the wires on the faulty unit , remove it then solder in the new unit and button her back up. When I get my Paso back, I will do the coil relay mod and ride. Thanks guys for all your help. :D


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 Post subject: Re: Replacement coils...
PostPosted: Wed Jul 13, 2016 9:24 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
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Location: southern Germany
model: 750 Paso
year: 1987
Quote:
Mike used his ohm meter to check continuity of the neg wire off the horizontal coil to the CDI unit and found no resistance (an open circuit)

Which is what Hamish suggested a while ago. There`s something I don`t get tho. If there's no continuity on the neg. wire from coil to CDI unit what does this have to do with the pick-up?
If he actually measured the continuity or resistance of the pick-up (connector) it would make sense to remove the alternator cover and measure directly at the pick-ups.
If just a new pick-up was soldered to the old wiring the problems might still be there if the culprit is actually not the pick-up but in the wiring to it.


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 Post subject: Re: Replacement coils...
PostPosted: Wed Jul 13, 2016 3:54 pm 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 235
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Yes, he did exactly what Hamish suggested I do next. I just didn't have the guts to do so because I believed that the pick or wiring in the case was probably the issue because in my mind y'all had helped me eliminate the other elements in the equation (and I knew it was time for professional assistance). I don't comprehend the process with the ohm meter and no resistance, but I'm willing to play along. :D

I will ask Mike at Nichol's to closely inspect the wiring within the case for any faults. Thank you again for you interest and time. :beer:


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 Post subject: Re: Replacement coils...
PostPosted: Fri Jul 29, 2016 1:41 am 
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Joined: Fri Nov 13, 2009 4:33 pm
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Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Just to follow up for the record, the pick-up was replaced (soldered to the existing wiring within the case) and all is well. The pick-up was indeed from Rick's Motorsport Electrics and the part# on the box label is 21-509. I've put the original 29 year old coils in a nice safe place and replaced them with coils from a carbed '99 M900 (a mere 17 years old). Cheers!


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 Post subject: Re: Replacement coils...
PostPosted: Wed Oct 05, 2016 2:26 pm 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 235
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Happy Paso. New pick-up, merely 17 yr old coils and some refurbished fairings. Over 48K miles and she is still a beast. Thanks to gentlemen in this special forum.


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 Post subject: Re: Replacement coils...
PostPosted: Fri Oct 07, 2016 5:31 am 
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Joined: Sat Jul 23, 2016 6:07 pm
Posts: 8
Location: Poland
model: 750 Paso
year: 1990
Great bike!

Ps. I've also change to M900 coils in my 1990 Paso - Monster coils rule! :D


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 Post subject: Re: Replacement coils...
PostPosted: Fri Oct 07, 2016 8:05 am 
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Joined: Sun Jan 16, 2005 12:00 am
Posts: 257
Location: The Netherlands
model: 750 Paso
year: 1989
randtcastell wrote:
Happy Paso. New pick-up, merely 17 yr old coils and some refurbished fairings. Over 48K miles and she is still a beast. Thanks to gentlemen in this special forum.


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