125 WITH NO SPARK

Lambertini era singles (125 and 250 - half v-twins)
EVguru
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Re: 125 WITH NO SPARK

Post by EVguru »

ALL of the CDI modules simply fire when the voltage on the trigger input rises above a certain level.

The advance comes from the shape of the voltage produced by the pickup and the fact the voltage produced by the pickup increases with rpm.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Aye Leonard and Paul,

Thank you Paul, that is what I understood from our previous conversations.

The problem I have and Leonard's symptom's appear to mimic, is that both the #323921 (black) and #32398112 (blue) CDI modules are giving me the same response as each other and mine have been taken to an 'electronic' test speed of 20,000rpm and given good regular sparks throughout the test. They have also given good sparks when mounted on a test rig, along with the stator and rotor, but the test rig wasn't able to take the rotor above 3,000rpm.

This time on the bike I have tested both CDI modules, with a Gunson Multi-meter measuring vAC between the feed (green cable) from the low tension coil (original, remounted) to the green CDI terminal and the CDI earth mount on the frame and engine. At the same time using the Accuspark 8000 to view the movement of the 'ANT' mark on the rotor in relation to the centreline of the camshaft, or the engine 'RPM' using the 2stroke scale to take into account the "wasted spark" of the system.

At tickover (1,200-1,300rpm) vAC is 115 - 120vAC. With a steady increase of throttle, the revs rise to 3,000 - 3,500rpm, at this point the vAC has risen to 180 - 185vAC and the engine begins to misfire, with some backfiring of unburnt fuel in the exhaust. If the throttle is steadily opened further toward half throttle, the revs rise to 3,500 - 4,000rpm, the vAC increases to 200 - 205vAC, the 'ANT' mark appears to move to the left ( anti-clockwise), against the direction of rotation of the crankshaft, by approximately 5° and then the vAC collapses and the engine cuts out. I repeat that this happens with both CDI modules.

This is the same pattern of failure that I was acheiving with the original low tension and trigger coils. I changed the trigger coil only for another (Indian, Lambretta type 12) and the pattern of failure was repeated. I then changed the low tension coil for a "pattern" low tension coil and acheived the same pattern of failure, using both CDI modules. I then sent the whole system away for testing and my original Italian trigger coil was seen not to produce the negative half of a wave signal. The Indian, Lambretta type 12 trigger coil that I had fitted was deemed to be of poor quality and not located correctly in relation to the magnet cut-outs on the inside of the rotor. A quality OME Ducati Electronica " unobtainium" was fitted and appeared on the test rig to perform satisfactorily. My original low tension coil was found to be in good condition and of better quality than the "pattern" one that I had fitted. So the original was re-fitted to the stator. All the wiring has been insulated and painted with insulating paint and appeared to function well on a limited rpm test rig.

To my untutored brain there is possibly a an intermittent breakdown of the insulation when the vAC reaches 180vAC. Then a total breakdown of insulation when the low tension coil output reaches vAC200 - 205vAC. Or, the low tension coil voltage "spikes" above 200vAC and breaks down the insulation? Both events prevent any HT spark from the CDI module and cut the engine. There is no gradual loss of a spark, it is as though a switch is thrown 'OFF'.

I have today made arrangements to potentially put the bike on a dynomometer and see if we can replicate this series of events, with an oscilliscope etc connected, to record whatever we may record, and an auto electrician to interpret whatever we find! We shall see! :wink:

Thank you for your interest and Good health, Bill
125H
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Re: 125 WITH NO SPARK

Post by 125H »

Hi Bill,

hope you have some success on the rolling road, I was just looking at my rotor and there are two scribe marks on the outside that appear to be 'man made' about level with the trigger plate inside, do these mark have to align with anything when the crank is in a particular position of rotation or the cam is in a position in regard to the timing belt pulleys?
I have never had CDI ignition before or owned a motor scooter but I doubt the Morini factory made those marks for no reason.
I know, I'm clutching at straw's again but all information can be useful at some point.

Regards
Leonard.
125H
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Re: 125 WITH NO SPARK

Post by 125H »

Hi Bill,

a bit more information Nuova Ray in Italy have a CDI unit that they say is a direct replacement for Ducati 323921 their part number C31 its expensive though at 95 euro plus shipping but if our problem does turn out to be CDI related then personally I will raid my 'piggy' and get one.

Regards
Leonard.
125H
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Re: 125 WITH NO SPARK

Post by 125H »

Hi Bill,

a bit more info, this is from the Dutch website: -

'If the advance goes the wrong way around then probably just like the on the 3.5 and 500/501 there is a wrong mix of pick up and transducer'

I assume from this that they refer to the timing mark moving to the right instead of to the left as one would expect to come into line with the centre cam shaft.

just thought it may be worth checking when you get rolling

Regards
Leonard.
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Ming
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Re: 125 WITH NO SPARK

Post by Ming »

125H wrote: 05 Sep 2022 09:59 ...'If the advance goes the wrong way around then probably just like the on the 3.5 and 500/501 there is a wrong mix of pick up and transducer'...
Yes - but as I understand it, your 125H does not have a pick up similar to those on the twins. It still (to me) points to a possible problem with the trigger coil on the stator, whick I understand takes it's place?
125H
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Re: 125 WITH NO SPARK

Post by 125H »

Hi Ming,

I am sure you may be right, its either the trigger coil or the transducer or an incompatibly of the two parts and what may work on a V twin may not work on a 125H they are both very different.
Having spent quite a bit of cash having my stator restored and rewound I shall not be too happy if it is the coil, as it should have been returned in a workable condition.

I think its now a matter of testing and hope Bill finds a solution if not I will have to consider a complete new ignition system being built which I doubt can be done in the UK

Regards
Leonard.
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Re: 125 WITH NO SPARK

Post by MickeyMoto »

Try Boyer Bransden...
125H
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Re: 125 WITH NO SPARK

Post by 125H »

I will try them again, but was certain they only make ignitions for British classics, thanks for your input.
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Aye MickeyMoto and Leonard,

I have already approached Boyer Bransden and they politely declined, saying that they produced nothing suitable.

The problem with the 125H, is that our trigger is not located on the end of the camshaft, as with all the other engines. If it was, then an Electrex STK169 set up could have been the way to go.

Regards, Bill
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Re: 125 WITH NO SPARK

Post by MickeyMoto »

Bill,
What do you have on the left hand end of the camshaft? Is the cover still there and can a trigger like the 350 be fitted?
125H
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Re: 125 WITH NO SPARK

Post by 125H »

I to have been in touch with Boyer and they don't offer anything for a Morini and I think fitting a trigger to the left hand end of the camshaft would be prohibitive in time effort and cost, that's if it could even be done.

I am speaking to a company called Beck on the continent who has built ignitions for the 350 V twin but again the 125H is an odd - ball system borrowed from a motor scooter and most ignition builders will not want to get involved, there is also Igni Tech who may have something, there are ignition systems only that will fit or can be modified, but as we also need a charging system they are of no use either, unless it was for a race bike. I will keep digging to see what is around. Most on the continent I have been in contact with feel the problem is within the pick up coil. I had all my coils rewound - but was it done correctly.
125H
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Re: 125 WITH NO SPARK

Post by 125H »

Unfortunately neither Beck, Sash, Horsepower or Boyer, offer anything for the 125H so the possibility of new replacement ignition systems is looking very slim or non - existent.

One other thought Ducati Electonnica would not have made the stator plate for Morini alone it was probably an off the shelf stock item for a Zundap scooter. (or similar). So it may follow that a stator from a Zundap 125 may work on the 125H if all else fails, but that's a 2 stroke and 2 strokes normally have different coils.

Personally, I now think its a matter of testing tracing fault finding and possible correction, of incompatible parts, as finding a new ignition system looks ever more unlikely. These engines must have worked once so should do again. I wonder what we are missing?

Regards
Leonard.
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

These engines must have worked once so should do again. I wonder what we are missing?
Exactly! :twisted:

Keep sitting on your hands! :wink:

Regards, Bill
125H
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Re: 125 WITH NO SPARK

Post by 125H »

Hi Bill,

thanks for reply, I have decided not to sit on my hands as I cannot work the bottle opener, but eagerly await your findings.

I was looking at uTube yesterday and there is quite an interesting one called I think it was Morini advance, the operator had marked the rotor with a red line across the ANT mark and it was quite good see this move from right to left under a strobe light, as the revs increased, wish mine was doing that!

Regards
Leonard.
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