75 860GT ignition question

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blaine.hale
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Re: 75 860GT ignition question

Post by blaine.hale » Fri Aug 12, 2016 8:14 am

Craig in France wrote:Hi Blaine,

1. Are you still getting consistent sparks on both plugs? If one or other is intermittent, here's a thought (I'm assuming that you've already checked/changed HT leads and caps):

2. Have you checked the resistance of the ignition generator coils and the pick-ups? (They're an integral part of the stator unit if I remember right). The workshop manual gives the following values:
  • Between ground and each of the white, red and green cables you should have no continuity.
    Between the green and white cables, you should get 285 Ohms+/-10% .
    Between the green and red, you're looking for 1000 Ohms +/-30%
3. Really dumb question :-D . You sure the ignition switch isn't playing up?

4. Even dumber question: you SURE you're not running an engine stop relay? I thought the ignition switch worked thru it? If I'm insulting your intelligence here, please feel free to say so ... :doh: . It's been nearly 30 years since I had a 860, so you'll have to forgive me! Maybe I need to look at the wiring diagrams again ...
1. Yeah, still getting nice blue/white. I'm using these leads https://store.bevelheaven.com/Electrics ... -Wire-Set/
I've also tried the stock leads and produced the same spark.
2. I'll check all that tonight but I did do an OHM check and it was within spec with what was in my Haynes.
3. I don't have an ignition switch. It's removed from the factors all together. If it runs, I'll have to kill the gas or let it die in a high gear for now haha.
4. TOTALLY sure. It's still in the headlight bucket, that I'm not using, and I'm not using any of the stock electronics apart from the ignition/transducer setup. I've isolated everything very well just so I can get the dang bike running. You should be able to remove the ignition switch and engine stop relay on these and it run just fine. Those are only necessary if you want to stop the motor or prevent it from being stollen. I'll integrate those back in the system once I actually get the motor running. Baby steps!

I think I may do a video tonight to show you guys what I'm working with. That may help things. Virtually diagnosing issues ain't exactly easy!

wdietz186
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Re: 75 860GT ignition question

Post by wdietz186 » Fri Aug 12, 2016 6:59 pm

Go ahead and order the ignition.

Lumpy
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Re: 75 860GT ignition question

Post by Lumpy » Fri Aug 12, 2016 10:00 pm

Call me simplistic...........but it sparked and would'nt run. You swapped transducer leads..........runs like a clock..........you mess with transducer leads and it sparks and won't run again....................surely this has got to be mixed transducer wiring again..........

blaine.hale
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Re: 75 860GT ignition question

Post by blaine.hale » Sat Aug 13, 2016 7:24 am

Lumpy wrote:Call me simplistic...........but it sparked and would'nt run. You swapped transducer leads..........runs like a clock..........you mess with transducer leads and it sparks and won't run again....................surely this has got to be mixed transducer wiring again..........
Wish I could say that were the case. There's 4 configurations you can have with those wires. I don't mean swapping the colors on the transducers, those are always labeled and the same blanco/rosso/verde (outside edge.)
Basically, I swapped which transducers the leads were going to and in that I swapped which transducers the spark cables were going to. A total of 4 configurations tried. Kicked the bike over about 10 times on each config and got nothing.

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Re: 75 860GT ignition question

Post by blaine.hale » Sat Aug 13, 2016 8:54 am

blaine.hale wrote:
Craig in France wrote:Hi Blaine,

1. Are you still getting consistent sparks on both plugs? If one or other is intermittent, here's a thought (I'm assuming that you've already checked/changed HT leads and caps):

2. Have you checked the resistance of the ignition generator coils and the pick-ups? (They're an integral part of the stator unit if I remember right). The workshop manual gives the following values:
  • Between ground and each of the white, red and green cables you should have no continuity.
    Between the green and white cables, you should get 285 Ohms+/-10% .
    Between the green and red, you're looking for 1000 Ohms +/-30%
3. Really dumb question :-D . You sure the ignition switch isn't playing up?

4. Even dumber question: you SURE you're not running an engine stop relay? I thought the ignition switch worked thru it? If I'm insulting your intelligence here, please feel free to say so ... :doh: . It's been nearly 30 years since I had a 860, so you'll have to forgive me! Maybe I need to look at the wiring diagrams again ...
1. Yeah, still getting nice blue/white. I'm using these leads https://store.bevelheaven.com/Electrics ... -Wire-Set/
I've also tried the stock leads and produced the same spark.
2. I'll check all that tonight but I did do an OHM check and it was within spec with what was in my Haynes.
3. I don't have an ignition switch. It's removed from the factors all together. If it runs, I'll have to kill the gas or let it die in a high gear for now haha.
4. TOTALLY sure. It's still in the headlight bucket, that I'm not using, and I'm not using any of the stock electronics apart from the ignition/transducer setup. I've isolated everything very well just so I can get the dang bike running. You should be able to remove the ignition switch and engine stop relay on these and it run just fine. Those are only necessary if you want to stop the motor or prevent it from being stollen. I'll integrate those back in the system once I actually get the motor running. Baby steps!

I think I may do a video tonight to show you guys what I'm working with. That may help things. Virtually diagnosing issues ain't exactly easy!
Just ran an ohm check. Nothing when testing each wire to ground, as expected. Green to white gives me 277ohm on each set. Red to green gives me 0ohm on both sets. That could be a problem?

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Craig in France
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Re: 75 860GT ignition question

Post by Craig in France » Sat Aug 13, 2016 2:06 pm

blaine.hale wrote: Just ran an ohm check. Nothing when testing each wire to ground, as expected. Green to white gives me 277ohm on each set. Red to green gives me 0 ohm on both sets. That could be a problem?
Sorry - I've deleted my original reply to your post. It's not right ... :doh:
Last edited by Craig in France on Sat Aug 13, 2016 2:26 pm, edited 1 time in total.

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Craig in France
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Re: 75 860GT ignition question

Post by Craig in France » Sat Aug 13, 2016 2:11 pm

blaine.hale wrote:Wish I could say that were the case. There's 4 configurations you can have with those wires. <snip>
Blaine, FWIW:

If you have the original cabling, you shouldn't need to be doing this. One of the two 3-wire cables should be red. It goes to the transducer that sparks the BACK pot.

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Re: 75 860GT ignition question

Post by Lumpy » Sat Aug 13, 2016 3:20 pm

Could the insulation on the wiring to the stator be rotten and maybe by moving the wires you had a moment when they were'nt contacting each other??
I had this issue on a Bosch ignition. Basically with age,oil and heat the insulation goes rotten on the wiring and contact each other. Bad news is the only way to check is strip the outer off to expose the inner wires. Maybe with a multi meter connected and wiggling the wiring at the stator end it may show. Although if it's original stator wire replacement may be worth doing anyway. If you plan to keep original ignition this wiring will give you trouble at some stage.........so will the stator.........and the stop relay.........and the regulator........and the switchgear.........and the fuse box..........Bevel drive Ducati's, only those willing to tinker need apply.

blaine.hale
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Re: 75 860GT ignition question

Post by blaine.hale » Sun Aug 14, 2016 5:27 am

Craig in France wrote:
blaine.hale wrote:Wish I could say that were the case. There's 4 configurations you can have with those wires. <snip>
Blaine, FWIW:

If you have the original cabling, you shouldn't need to be doing this. One of the two 3-wire cables should be red. It goes to the transducer that sparks the BACK pot.
Really? Hmmm. Mine are just 2 leads coming out of the crank case, both black insulation. In both of those leads is a red, green and white cable. They're identical. I don't know why they would be anything but stock. The whole bike was bone stock, unmolested, super low mileage.

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Craig in France
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Re: 75 860GT ignition question

Post by Craig in France » Sun Aug 14, 2016 11:57 pm

blaine.hale wrote:Really? Hmmm. Mine are just 2 leads coming out of the crank case, both black insulation. In both of those leads is a red, green and white cable. They're identical. I don't know why they would be anything but stock. The whole bike was bone stock, unmolested, super low mileage.
Hi Blaine,

Please see the attached scan of page 149 of the factory workshop manual. Note that the boldening is Ducati's own, not mine!

Image

The text reads:
"Two three-wire cables come out of the stator and must be connected to their transducers. The red cable must be connected to the transducer of the vertical cylinder"

And that's the way I remember it too. However my memory may be fooling me; so at this point it would be good to have confirmation from a present-day owner.

If it is confirmed, that suggests someone's played with your pickups or starter coils in the past. Which might explain a lot -?

blaine.hale
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Re: 75 860GT ignition question

Post by blaine.hale » Mon Aug 15, 2016 4:47 am

I think I may relent to buying the aftermarket ignition and coils for now. I'm too anxious to get this long project on the road. If it fixes the issue, great. If it doesn't I can always sell the ignition and know my problem lies elsewhere.

That red cable thing is weird. I'll have to go check on my buddies 900 to see what that looks like.

**edit: Ordered a sachse ignition and 2 5ohm dynatech black coils. Also have a buddy who is currently going through his 900 GTS coming over this evening to compare systems.

wdietz186
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Re: 75 860GT ignition question

Post by wdietz186 » Wed Aug 17, 2016 6:38 pm

Glad you saw the light, even if it had decided to run for you it wouldn't have for very long.

blaine.hale
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Re: 75 860GT ignition question

Post by blaine.hale » Thu Aug 18, 2016 5:22 am

wdietz186 wrote:Glad you saw the light, even if it had decided to run for you it wouldn't have for very long.
Just how bad are those stock ignitions?

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Craig in France
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Re: 75 860GT ignition question

Post by Craig in France » Thu Aug 18, 2016 11:54 pm

blaine.hale wrote: Just how bad are those stock ignitions?
Bill will have more to say on this than me ! But, FWIW:

'All right when they're all right' :-D . But you can fry the transducers, and it seems that the pick-ups/generator coils may be vulnerable. But then again, we are talking about 40 year old electronics here ... :shock: . And coils can be re-wound. And replacement transducers found - you can even buy them new!

And I'm still running the original Ducati electronic ignition on my single ... :vroom:

The weak point on the 860s was always the engine stop relay, an overly complicated solution to a simple problem. To be fair to Ducati, they quickly modified the original installation. After that, for some people the naughtiest bit was the abrupt advance step (see below) which they blame for big-end failure. But I can't say it particularly presented me with any grief. (The Bosch system used on later Laverdas, on the other hand ... :wah" >:|!!!)

Image

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Re: 75 860GT ignition question

Post by Lumpy » Fri Aug 19, 2016 12:18 am

I've had my GTS for 32 years. Second road bike I ever owned. She's only got 78k on the clock and the vast majority done in the early days. More civilzed machinery is my day to day choice these days and the old girl only comes out to play on sunny Sunday's or if I'm feeling a bit nostalgic.
During our time together she's on to her third Electronca stator unit. She always came home but would do so on one lung below 3000 rpm. The last one I had re-wound as I could'nt new. The transducers are original. I have recently purchased a Sache unit but am yet to fit it. The old girl is in the midst of a substantial upgrade but it's going to take time.
As Craig pointed out aside from the unreliability of the unit the single step advance is a pain. There is a distinct leap in power at the advance point and I for one agree that this is hard on not only big ends but the entire drive train.
Upgrades are'nt cheap. Guess maybe you need to ask yourself what you want out of her. Going to do some miles???? Get a new ignish. If she's just for the odd putt down to your favourite beverage outlet or your not one to hang onto your bikes for generations like me maybe the original unit will suffice. Bit of an equation of emotion over need divided by disposable income really.

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