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[Florida V65 1992] Problem with ECU/CDI unit

Discussion in 'Small Block' started by Grimshaw, Sep 8, 2019.

  1. Grimshaw

    Grimshaw Just got it firing!

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    Hello guys, this is my first post in the forum, so greetings to everyone! I am a proud owner of a Florida V65 (1992) since recently and I hit a problem I am having trouble with, keeping it in the garage.

    The bike was running fine otherwise, but I noticed that once it got warm from a few miles the engine would start misfiring (mostly on idle), so whenever I stopped at a red light it would stall in a few seconds if I didn't rev it. I thought it was the carbs for a while but while tuning them I noticed the left plug didn't have a proper spark, which led me down the rabbit hole of testing the ignition.

    First thing I noticed was the ignition coil on the misfiring side was getting really hot, while the other was at a neutral temperature. In fact, it gets hot just by turning the key and not turning on the engine. I tested the right side coil and 2 others I had around and they all get hot just the same, but all these coils work fine in the right side.

    So I thought it had to be a faulty CDI unit, I got the two I could find (used Motoplat ones which ran in a similar bike). The left side CDI in the bike was already a similar Motoplat one when I got the bike, while the right one is different and has a white stamp with moto guzzi branding on it.

    Though, I tried all these 3 motoplat CDI and they all give me the same result, the coil keeps getting boiling hot. As reference for the installation I was looking into this diagram:
    http://www.thisoldtractor.com/guzzi...OZtKV8D--c3XiubseZjJ92uxCfXZHf7sauy-kmMdrJ1yA

    From the diagram two things aren't clear to me at all: On the right cdi, the red wire splits into a small cylinder (which seems to be a resistor), which was grounded in the bike chassis, but on the diagram its connection seems to go into the right coil??

    The other aspect is that part of the circuit relating to the left coil red wire, which goes into some other component before returning to the right coil.

    Can anyone please shed some light on what could be happening here and help me interpret the diagram??
     
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    It seems you have replaced everything except the coil that was misfiring. I'd try that first. If you have already and didn't state that then in may be a faulty ignition control module.
     
  3. Grimshaw

    Grimshaw Just got it firing!

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    I actually tried permuting the components to see what worked with what and all the coils seem to work provided they are connected to the non-motoplat CDI. That allows me to shift the problem from left to right as well

    I could not find the original CDI so I have 3 motoplat ones that according to online reference, are compatible with moto guzzi v65 and the motorcycle came to my hands running on one..

    To put it very practically, on my left side, once I turn on the ignition switch, the ignition coil starts getting current and heating up, continuously. Considering such a coil discharges when the current is cut off, I do have a confirming symptom to this: Unplugging the left CDI causes the spark plug to fire and burn any leftover gas in the cylinder. (All of this without turning the engine on at all).

    So, the coil is clearly getting current when it shouldn't, which seems to me like a problem in resistances (maybe grounds as well) or something about the circuit is just wrong.

    Is it generally safe to connect multiple ground wires to the same slot in the chassis? Can someone explain me what I think is named a ballast resistor from the diagram?

    Also, I wonder if the Pickup itself could be a cause here? I'd say no because if I swap the CDI's, I swap the problem to the other side, which probably indicates both connections of the pickup are ok.
     
  4. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Doubtful the pickup is the problem. I think you just have to locate a CDI unit that works. Are there any dealers in your area that might help to locate what you need?
     
  5. Grimshaw

    Grimshaw Just got it firing!

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    I actually went to the PIAGGIO repair center in my city (it doesn't get more official in my country) and they just told me the capacitor unit is not obtainable anymore.
    They told me to just try to find it in the obscure providers, and it's not even the original ones.. So that is what I did
     
  6. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    That is unfortunate. You might try breakers (people who salvage parts from bikes) for a used unit, but then there is no guarantee it will be good. Best of luck on finding a unit. If not, the bike may need to be parted out so you can recover some of your investment.
     
  7. Pescatore

    Pescatore Just got it firing!

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    The Motoplat modules were prone to failure. My V65 was converted to old fashioned mechanical points by previous owner, so I'm not sure what's involved with that.
    Best of luck.
     
  8. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    That would certainty solve the issue. Probably V50 points plate would do the trick if it can be mounted. I don't know if the cam would need to be changed to operate the points.
     
  9. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    That would do the trick. Probably a V50III points system if it can be mounted. Also I don't know if the cam would have to be changed to operate the points and advance system.
     

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