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 Post subject: Replacement coils...
PostPosted: Tue Jun 07, 2016 5:06 am 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 233
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Gentlemen: my dear Paso's horizontal cylinder skipped a beat the other night, and dropped out completely on the road this morning. I just did a major service on my pristine 750 and I had its Del'Orto PHM40s rebuilt and synched. I've switched the coils to diagnose the problem and sure enough, the dropped cylinder followed the bad coil. So' I'm looking for replacement coils. I've read the F.A.Q. regarding coils and I think I've found a nice pair of replacements on eBay from a 2003 M900 Monster: Ducati Monster 800 2003 Ignition Coils Coil Spark Plug Boots Wires J040005D07

Could y'all have a look at this link and give me your opinion as to whether these will work as I think they might:

http://www.ebay.com/itm/271897147884

Thank you very much for your help/advice/opinion and for your time and attention.


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 07, 2016 7:46 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4978
Location: southern Germany
model: 750 Paso
year: 1987
These won`t work. The S2R 800 has a fuel injection so the coils will have around 1 ohm primary resistance only.


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 07, 2016 9:33 am 
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Joined: Tue Jul 24, 2012 8:54 am
Posts: 241
Location: Broome, Western Australia
model: 907 I.E.
year: 1992
I purchased a pair of Dynatek coils about 12 months ago. DC3-1's from memory.

Cheers.

Nick.


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 07, 2016 5:04 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4978
Location: southern Germany
model: 750 Paso
year: 1987
another option:
http://www.hognutz.com/32-0484/


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 07, 2016 5:56 pm 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 233
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Thank you gentlemen for the responses.

I was silly to forget the 2003 M800 was fuel injected. Thanks for the correction.

I've been considering the 3 or 5 ohm coils from Dyna. Which of the 2 types would y'all suggest?

Wow, the Volt Tech coils are a great price.

I was thinking of this link for coils as well, I believe these are a viable option:

http://www.ebay.com/itm/1999-Ducati-M90 ... Sv&vxp=mtr

They are from a carbed monster. Do you think they are appropriate?

If I go with the Dyna coils or Volt Tech coils I would have to slightly modify the existing wire terminals. I'd rather leave the stock push-on terminals at those wires going to the coils rather than change them out to ring terminals so they would attach to the new coils.

Is that silly and not actually an issue for those that have used the Dyna type coils?

This link has me most interested, any thoughts?

http://www.ebay.com/itm/BOBINA-ALTA-TEN ... 0b&vxp=mtr

Thank you again for your assistance. Thank you very much.


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 07, 2016 6:36 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4978
Location: southern Germany
model: 750 Paso
year: 1987
the theory is that the 3 ohms coil has a stronger spark but gets warmer. I don`t think you`ll notice a difference between the two, tho.
The coils from a '99 would be ok as Ducati went from carbs to fuel injection in 2000. However I`d probably prefer a good aftermarket coil to an original.

No need to modify the wiring btw. if you get a few of these:

ImageImage

PS: there are also:
http://www.ebay.com/itm/Harley-dyna-3-o ... -H&vxp=mtr
http://www.ebay.com/itm/Dyna-coils-5-0- ... YN&vxp=mtr


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 07, 2016 9:13 pm 
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Joined: Fri Nov 13, 2009 4:33 pm
Posts: 233
Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
Thanks again for all your advice and coaching. Seriously, the value of the help on this forum is very high. Makes all the difference in my outlook on life.

I made a decision and placed the order. Delivery Monday! I don't think anything else will fail for a while on this 29 year old machine with 48,000 miles. Ha, Ha. :)


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 Post subject: Re: Replacement coils...
PostPosted: Wed Jun 08, 2016 8:32 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4978
Location: southern Germany
model: 750 Paso
year: 1987
don`t forget you`ll need new spark plug wires, too


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 Post subject: Re: Replacement coils...
PostPosted: Wed Jun 08, 2016 3:51 pm 
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Location: San Francisco Bay, California USA
model: 750 Paso
year: 1987
paso750 wrote:
don`t forget you`ll need new spark plug wires, too


Thank you, I'm on it. The existing HT leads from my original coils are so stiff (and I imagine brittle as well) that I'd bet that the fault in my horizontal cylinder's coil is in that spark plug wire.


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 Post subject: Re: Replacement coils...
PostPosted: Wed Jun 08, 2016 9:51 pm 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1292
Location: SF Bay Area
model: 750 Sport
year: 1990
On the original coils, the HT leads are not replaceable, and glued in place. At this age of the bikes, you should replace the coils and wires, as the stock ones are near death, and almost all of the aftermarket options out there will produce a bigger spark than the stock units. Coils die over time and use, and are quite well passed due.

Cheers, Phil

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1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Replacement coils...
PostPosted: Mon Jun 13, 2016 1:50 pm 
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Joined: Sat Mar 08, 2008 9:29 pm
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Location: Greece
model: 750 Paso
year: 1989
.... same time , same stop firing on front cylinder but after checking coils and electronic boxes finally ..... pick-up zero ohm.
Rear cylinder pick-up 116 ohm. New pick-ups searching start ....! :!:

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 Post subject: Re: Replacement coils...
PostPosted: Mon Jun 13, 2016 2:14 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4978
Location: southern Germany
model: 750 Paso
year: 1987
did you measure at the pick-up? If not it might just be a broken wire (where it comes out of the engine cover)


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 14, 2016 8:38 pm 
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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
Well, I thought I diagnosed a bad coil. I misdiagnosed the problem. What a goof... Anyway, I got a lovely set of used coils from a 1999 M900 with 17K miles for US$59. Came with fine HT leads. Both produce a nice spark for the vertical cylinder. I will have to takes Phil's advice and replace my 47K mile 29 yr. old units with these. Since I've still got no spark for the horizontal cylinder with any coil, I switched out the CDI units to see if one was acting up. No change in condition. I then examined all the existing wiring and wire terminals. All looks quite good: original condition, unmolested, and undamaged. I wiggled and jiggled wires and terminals to no avail— still no spark to the horizontal. I then took Gerhard's advice to check voltage at the coils. First, battery reads 14.4 volts. With the ignition on, voltage at each coil reads 11.5 volts. Am I checking voltage at the coils properly by just turning the key to on for the check, or should I press the start button, or take other steps? I thank you for all your help and support and for your kindness.


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 Post subject: Re: Replacement coils...
PostPosted: Tue Jun 14, 2016 9:59 pm 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1484
Location: Newzealand
model: 906 Paso
year: 1990
3 volts seems a lot to loose between the battery and the coil, but it sounds like your doing it right . if you have power to the coils the next thing I would do is to check the continuity of the wire between the coil and the magic box ( the coil neg ).
If Im understanding correctly you now think the pick up coils are ok ? ..... just that it seemed to fit perfectly :) are you sure you don't have an intermitant fault with the pick up , as G sez a broken wire would do that AND the plastic insulation around any break in the internal wires may look fine on the outside .. Hook wires for that pick up to your continuity tester and then gently pull the wire out straight .... the idea being that if the wires are broken inside the insulation pulling will stretch the plastic and the broken ends of the wire will separate and show as an open circuit . The most common places for such a fault are where wires go thru things ... be it a cable tie , a case grommet or where the terminals are crimped onto the ends of the wires :)

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 Post subject: Re: Replacement coils...
PostPosted: Wed Jun 15, 2016 8:35 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 4978
Location: southern Germany
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...
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. :wacko:

A 3V voltage loss is a lot. If you`d press the starter button it would drop even more. Take a close look at all electrical connections, specially the ground points, the condition of the connectors and the crimping. Sometimes if a wire moves (and specially if its old and oxidated) it will begin to break just behind the crimped connector and only hold by a few strands. As Hamish pointed out the negative wire from CDI unit to coil may be interrupted in which case it wouldn`t get any 'firing signal'. Clean all connections. A great part of that voltage loss may be caused by the ignition and the starter/kill switch. If you can`t restore the voltage check the FAQs for the coil wiring mod (no wiring needs to be cut if you do the simple mod).

Low voltage can be a reason for a cylinder dropping out but usually it`s the rear cylinder. It seems that as the crankshaft & flywheel rotate counterclockwise and the front cylinder fires first there`s not enough power left for the rear cylinder ignition which then will only fire ocassionally or kick in at higher rpm when the overall voltage increases.

Assuming the spark plugs are fine, you`ve ruled out the CDI units by swapping them as you already did, you fixed the voltage loss and didn`t overlook anything the issue must be before the CDI units. You`ve gone through the causal chain from its end backwards towards its beginning which is the right way to do it. :thumbup:


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