1980 900S/S Ducati ignition problem

[DaveH]

One of my original Bosch transducers finally quit working. I tried a "good" used one and it still ran poorly. I tried to update to the later Ducati transducer but it still ran bad. Installed DMC system it ran better. Now it surges so badly between 2,000 and 3500 rpm that it is almost unridable. Above 5000 rpm it vibrates (buzzes) like a single cylinder. I changed pick ups and wiring from the pick up to the coils & used a DMC ECU. None of this helped. I changed all wear parts in carbs...didn't help. I cahnged the carbs...didn't help. Talked to DMC factory...no help. I tried a different DMC ECU...No help. I've had this bike since it was new so it os not something I am imagining.
Any ideas where to go next????
HELP!!!!!!

[BevHevSteve]

did you:

Check for proper valve clearance?
Do a leak down test to check for ring and/or valve wear?
Replace exhaust gaskets and intake manifold insulators?
Make sure carbies are fully sync'd as per the instructions elsewhere on this forum?
CHeck spark plugs and wires?

[Vince]

My take,might not be right ,this is very common when an improved ignition is used on Laverdas,it shows up any poor jetting bigtime,try one
richer needle,I had surging in the midrange on my Pantah and it was fixed
by going to K8,it had I thinka K1.Dont know what needle is in yours.

[DaveH]

Thanks, I'll check those.

[DaveH]

I checked some of these things and here is some more info.

Valve lash is fresh & ok.
135 psi cylinder pressure on first kick, 165 psi after 3 kicks.
Exhaust gaskets are new.
Manifold spacers, 3 tries with new ones..nothing.
Carb spray..nothing.
Covered with silicone, no change.
Carbs are within 1/2cm, idle to 3500. In fact, the carbs were off 6-8cm and it ran no worse, surgewise, than when within 1/2cm.
Plugs, tried 3 different brands..no hlep.
Plug wire, tried resistor and solid core, no change.

The engine did not do this until I changed ignitions. All of the normal checks and tests have been made. To solve this is going to take someone who has been through it themselves I think. Is there any other ignition systems available???
Thanks again guys!

[Vince]

The witt ignision is MUCH SUPIRIOR than the stand ignision,why not try the differant needles,as I said it fixed the lean serge on my Pantah.Did you buy it from Wolfgang in Canada,try asking him,very cluey bloke.

[eric crutchfield]

Just got one of these DMCs from KAMNA Germany. I found them 'not-english-friendly' regards to the (german) instuctions supplied. Moto Witt hasn't bothered to respond. BUT, with a bit of digging (actually lots) I found out a couple of things. Have you popped the blanking grommett from the DMC box? Under there is a multi-position (15 positions) mini-switch that selects your timing curve. If you are on position one, you get buckets of advance, pretty quick.
I have been advised from Kamna to sart at position 3.
To further complicate matters, Kamna have supplied asian pick-ups that do not fit the backing plate they have supplied. Expensive, and not a 'easy-install' at all.