Bevel twin ignition (900 SSD)

Technical Help DesmoBevels
#1

I’d welcome any suggestions/recommendations on bevel twin ignition. The Forum seems to have been quiet on this topic for 3 years. My 900 SSD has eaten one or two Bosch ignition boxes in the past (and the regulator/rectifier went a few years ago, complete with melted wiring.) After a few problems with the Bosch boxes last year it ran fine all summer after cleaning all connectors.

Now moved up to Perth, so I’ve left my old network behind. This spring the engine fired up fine on one cylinder (Front), but lots of backfiring on the other (Rear), and on a test run no life from Rear cyl at all. Investigated: No spark on Rear cylinder, okay on Front. Swapped all components over to trace fault, reconnected and now getting sparks on both plugs, but engine will not start at all, occasional backfire. Newish battery, fully charged.

Odd resistance readings on Pickup connectors: 70 Ohms (Rear) and 0 Ohms (Front) Should be 220 Ohms. Note it was the FRONT cylinder that was working, and both plugs were sparking after reassembly, but perhaps not at quite the right time??

Pickups and/or pickup wiring seems to be a known problem. Maybe that was causing the problems that mysteriously resolved themselves last year (I’ll be honest - I haven’t had the LH engine cover off yet to poke the pickup wiring.) Has anyone successfully replaced the pickup wires, if so where do you get oil/heat resistant wire?

A few questions:

  1. How do I know for sure what is working and what is suspect - what’s my logical path into this?
  2. Should I assume pickup wiring is the problem and just replace that. I see Bevel Heaven in the US have a kit for just the pickup wiring replacement store.bevelheaven.com/Electrica … SS-Darmah/
  3. Would I be better off replacing the whole ignition system. Silent-Hektik have a replacement kit comprising pickups on a mounting plate, rotor, 2 coils, 1 ignition box: silent-hektik.de/Duc_900SS.htm Anybody tried this?
    (Mdina Italia seem to be fresh out of most OE and replacement ignition components)
  4. Is a Ducati dealer (Glasgow Ducati - 60 miles, is my nearest, they say they’re happy to look at it but not until September) going to be able to deal with this or am I going to have to go it alone? I can’t find any local bike specialist in Perthshire at all (nor even a club branch!)

Thanks, Dave

#2

Hello Dave.
The first place to look is the pickups, the original wiring was never rated for use in oil, sso it eventually turns to slime and sorts out so no signals form the pickups.
Andy at Mdina Italia does a service exchange on these, or Electrex World do them.
You will need to have them set up when replacing in the casing.

Kevin.

#3

Hi it’s a my Darmah also. I was out on a run, we stopped for coffee all was well up to now 30 miles, bike restarted ok but on pull away if had a misfire. Which didn’t clear. I managed to get it home. The k up’s end replaced not long ago. As the Bosch system is 1979 vinntage should I bite the built and replace the system, and which one Sachse from Germany OR another Mick

#4

Hello Mick, My 42 year old Bosch CDI boxes are still working well, I dont think they fail too often, have you had the pickups rewired, the message is a bit odd?
If your having a misfire I would start by fitting new Bosch W7C or Champion L86C plugs, not Iridium type plugs my Darmah hates them!
If the problem still persists have a look at the carbs make sure the main jet nut in the float bowl isn’t clogged with rust.
It could also be the coils, aagin mine are 42 years old and still going, can you swap them to see if the fault moves?
Also check your carb floats to make sure they are not leaking.
At a last resort you can change to Sachse, but it’s a lot of work.
https://www.elektronik-sachse.de/shopsystem-3/en/digital-ignition-zdg-3-23-for-ducati-beveldrive-bosch.html

Kevin.

#5

I have fitted a Sachse to my 900SS, didn’t find it too difficult, quite easy to set up,it does away with the bosch boxes so two less things to worry about, other advantage is you don’t need special tools to set it up i.e. the pick up setting tool. Tony Brancato put me off the Silent hektik system, telling me it is more fussy to set up.

#6

I feel the Sachse-ignition is perfect. It has the advantage of having a zero-pre-ignition up to 400 rpm which means no kick-back when step-starting the bike!
And after 35-45 years the pickups are simply burned.