Intermittent spark on an 860 GTS

[chrissipika]

I have been restoring an 860 GTS and now have the motor running nice and cleanly, however, after a short run the spark on the front cylinder becomes intermittent. I've swopped transducers - Ducati Electronica, no change.
I've checked the resistance on the generator feed - in line with the Haynes workshop manual, I've checked the continuity of the generator feed (but not yet all the way back to the generator) all is OK.
The motor will tick over for several minutes without a hiccup, once on a short run around the street it starts to cut out and run on the rear cylinder only. The front cylinder runs but is intermittent.
I have removed the spark plug cap whilst running and earthed but no spark is present.

I think I may have to renew the feeds from the generator but would be very happy to hear from anyone with ideas on extra tests I could carry our or checks to be done before I go anywhere near the ignition generator.

Thanks in advance
Chris.

[Lumpy]

Hi Chris,
might be worth removing your engine stop relay and try running it without it in the circuit. You will have to stall the engine to stop it but it will eliminate that as a problem. If that does`nt work I`m afraid you`ll probably have to get the ignition generator re-built. If I had to guess that will be more than likely where your problem is. New ones are no longer available (in Oz anyhow) but there are a couple of fellows over here who rebuild them. However I understand that some can`t be rebuilt. There is one guy over here who builds them up but puts all the diodes up under the tank so they are no longer in hot oil getting vibed to death, but it ain`t cheap. I had to have mine re-built a few years back and it cost about AUD$300, thats with the diodes still in the unit.

[chrissipika]

Hi Lumpy, many thanks for your reply. I've already tried disconnecting the engine stop relay and it makes no difference. Therefore I guess that I'll need to get the generator looked at / repaired, was yours a Ducati Electronica ignition system?

Who repaired yours for you in Australia?

I'll have to try and search down a repair shop in the UK, anyone out there who can recommend anyone?

I've heard that you can fit an after market 'Moto Witt' system, does anyone have experience of this?

[Lumpy]

Hi Chris,
I got my re-built stator from Road and Race here in Oz. He does a change over and I think it was about AUD$300 but that was a few years back. That one is still in there and is still running well. You can contact him through www.roadandrace.com.au There is another guy who rebuilds them in Oz and puts the diodes in a seperate unit under the tank but he was about $700. I don`t have his contact details anymore, but Phil at Road and Race could maybe tell you who it was.
Another option is Silent Hektik, a German crowd who makes a replacement and quoted me 600 Euro. I understand these are quite good as they have a progresive advance curve instead of the single step advance which many beleive is the reason the big ends fail on the GTS. You can contact him at www.silenthektik.com
And yes, mine is the old Ducati Electronica type. Hope this helps.

[conti-mental]

Hi Chris,

I had a similar issue years ago on my '75 900ss: it was OK cold, but would drop off one of the cylinders once it was warm, although it would kick back onto 2 once the engine revs were higher.
I replaced the ignition stator, which was OK because new ones were still available back then...Sorted.

However, I've just junked the whole setup, and fitted a DMC. The problem with this and (I suspect) the SilentHektic setup is that the flywheel has to go, so no more leccy start.

I can vouch for the fact that the bike is far smoother low-down. It's even cured the clutch grab it's had for the last 22 years!

This is the original advance 'curve'
http://uk.youtube.com/watch?v=X8rnFnd3Xdc
It all happens at around 1500 rpm

I'm hoping to have the new setup strobed tomorrow.

Cheers,

Andy

[mhrduc83]

I had a similar problem with my 83MHR the back plug would start to miss as the bike warmed up...kept thinking the carbies are out....then it just didn't want to start but eventualy started on the front cyclider and realised that the coil had eventualy died.

[chrissipika]

Many thanks for all your comments, I picked up a 'spare' ignition stator from Paul Klatkiewicz in Wakefield UK and fitted it over the winter along with some other tasks.

The 860 is running nicely again and ready for another summer.