Friends:

Thanks to the advice of everyone I have tested both coils. According to my old and primitive radio shack multitester (hey it worked fine hunting gremlins on my CB350 in college!), the primary is 5ohm, and the secondary is 11,000ohm. That is consistent at both coils. I cannot find any information on the specs of the Kokusan coils [sigh].

The voltage at the coil shows just under 10v, and this is likely optimistic. The voltage tester shows a fresh 1.5v battery at 1.7v, and a 9v battery at between 10v and 11v. I'd say its 9.5v, just like Slocum says it might be.

The plugs definetely get a bit wet after running. Typically, the bike starts hard at full choke, then evens out. But right around the time it might be ready to ride it won't rev, and the number one cylinder won't fire evenly. Finally, the bike stalls. It gets better a bit when the motor cools.

Applying a timing light shows the indicators holding steady, bright and true over 2700rpm. At idle to about 2000 rpm the you can't see if there are one or two indicator marks because the mark is jumping all over the place despite the strobe. You should see 2 marks according to the manual.

Thats all for now. Thanks for sharing the puzzle!

Brett

sounds as if the mentioned wiring modification would for sure do you good.
If you need to switch coils, there`re lots of aftermarket ones like Accel, Andrews, DynaCoil, Nology etc but beware they should not be less than 3 ohms resistance.

(Silent Hektik has some with 2,7 ohms but these, although if they may work, are recommended to use with their own CDI unit only).

I don`t have the data of the Paso coils at hand but the ones of the SS/Monster are:
primary 3.8-5.2 ohms
secondary 10.8K - 16.2K ohms
plug cap 5K ohms

Also if your coils seem ok aftermarket coils can create a much stronger ignition energy. This change should come with low resistance plug cables.

Using Champion RA6HC plugs also makes an improvement.

G.

First, is the carb float not flooding the engine? Does the choke fully release or close? Don't worry about the timing, forget it for now.

Print out the full color wiring diagram in the FAQ.

There are many items in the ignition that need to be checked:

Starting at the engine:

Pickups, wiring from pickups to ignitors, Ignitors, Wiring to coils, coils, spark plug leads and the plugs.

You can swap some of the items around with this system. Mark all of the wiring and then swap the leads from the pickups and the coils. If the vertical cyl has been failing the horizontal should now. By swapping the wiring you should be able to isolate the bad piece without going full crazy. As a caution, take some pictures of the wiring and make lots of notes. Tag all wiring so it can be put back.

I wish I was closer so I could help. You do have plenty of "adult" lubrication in the fridge??


Good luck.

Friends:

Yeah, I'll need plenty of that. [LMAO] Don't worry, their is always a bottle of something nearby.

This began in an effort to isolate the problem in the carb. Now I can't do that. Its clear that coil failure or not, there is low voltage to the coil. Running the mods to the electrical system seems sane and relatively cheap. I will go through the remaining electricals are well. Thanks for advice JC!

Original Kokusan coils are still available from Ducati. Perversely, the caps are not. Only $119 apiece!

I like the idea of using Monster coils. I will look into that. I will assume that these are for M750's. They might be cheaper. If anyone has an idea of what year M750's they used these coils, that will help narrow the search.

I probably still have carb problems, so this winter project may be going beyond the winter [smile].

Thanks for everyone's help and support!

Brett

I`m about sure, yes. I`m using an aftermarket flywheel for Monster/SS in the Paso. Pick-ups and CDI units are interchangeable like many other parts.

Instead of using original coils from another Duc I really would go for aftermarket ones although newer coils may already make an improvement. There was a comparison table between original coils from Ducati, some jap bike and some of the aftermarket ones I listed and the output energy (in mJ) was much less with original equipment. (unluckily that site doesn`t exist anymore)

Still I can understand that finding original used Duc coils on ebay is for sure easier and cheaper.
(I saw a new Andrews kit incl. coils and wires for a Harley for $199, just as a price indication)

G.

PS: as result of a short search: according to the NOLOGY webpage the coils for 750/900SS are ProFire PFC-30S (152 051 300)($94ea., 3 ohms model). $63 here:

Andrews are model CW140403 ($88, 3 ohms model).
Dyna Coils are CWDC3-1 ($138, 3 ohms model) or CWDC10-1 ($138, 5 ohms model).



and the only (aftermarket) ones found on ebay

Just a note so that the record is corrected:

Iceriani is correct about the specs of the original Kokusan coils. On deeper inspection of the poorly written, translated and organized Paso 750 shop manual, the coil output is listed as follows:

Pickup: 220ohm +- 5%
LV: 40ohm +- 5%
HV: 8800ohm +- 20%

Like the previous poster, I am inclined to believe that the LV number is 4ohm, not 40. I've never seen a coil LV in the 40's.

These are Dyna Coils...marked 3 ohm

Pasochist~

You using the original CDI units and pickup?

Brett

there`s no need to change