Good afternoon Gentlemen,
This 125H single problem is now spread across 3 threads!
Confusing for any future reference by a similarly suffering soul!
So, I shall post this information across all 3 threads and then stick with the "
125 with no spark" thread only. But, read the others for any further positive or negative developments.
I despatched my entire generator/ignition system, including both my original Ducati Elecctronica # 323921 and Ducati Energia #32398112 transducers (CDI/HT unit) to Rex's Speedshop, but due to staff problems and after 10 weeks, I requested that he return the whole lot to me. This he did, in short order and with no problems.
I then despatched the entire system to another experienced auto electrician, with the necessary oscilliscope facilities and experience of these scooter derived systems. After testing the individual components, he dynamically tested the system, with both the black Ducati Elecctronica #323921 and blue Ducati Energia #32398112 transducers in place. The component that appeared to be malfunctioning was my original trigger coil that was not showing a negative wave on the oscilliscope. The replacement (Lambretta type 12) that I had fitted did show the positive and negative waves but did not align with the cutaways in the flywheel that cause it to create the trigger signal. So another Italian trigger coil of better quality and fit was fitted to my stator and the working air gap checked. He too was of the opinion that there is nothing wrong with the quality of the Ducati components and system robustness, as a whole.
Today, I re-checked my valve timing, then fitted the stator etc. Connected all the stator wires to the black # 323921 CDI/HT unit and the RECT/REG and fired the engine up. A definite improvement to the ability to fire up and a good strong increase in the revs from a 1,300rpm tickover to half throttle (3,500-4,000rpm), when the stuttering re-appeared and any further opening of the throttle caused the engine to cut out abruptly. Using the timing light, a marginal movement of ~5°to the left of the 'ANT' mark on the rotor (advancing) preceeded the engine cutting out.
I then repeated the procedure, with the REG/RECT and ignition switch wires disconnected, with the same results.
The black # 323921 unit was then replaced, with the #32398112 unit, again starting with all of the connections made then disconnected and the exact same symptoms were recorded!
This would tend to discount the notion that the blue #32398112 unit is not a workable alternative to the black # 323921 unit. Or, the cause of this particular set of symptoms.
Interference to the trigger pulse is not uncommon if the earths are poor. Or the frame is heavily painted as the transducers rely on earth via the headstock.
To avoid this, I have renewed the earth lead from the REG/RECT mounting bracket to the upper rear crankcxase bolt of the engine and also used an additional white wire between both CDI/HT units and the REG/RECT mounting bracket bolts, to ensure a good earth between all of the components.
I am not convinced that fitting a
New and exact substitutes for the original black transducer with tacho output can be obtained from Alex Luzzi
will cure the problem.
Thank you all for your time and thoughts.
Good health, Bill