Advice on Repairing TCI Ignition System of Kipor/Honda Inverter Generator

[dial-a-monkey]

I'm seeking advice on repairing the TCI ignition system of a Kipor/Honda inverter generator that has stopped producing a spark. As I'm currently in a remote location in the Pacific sourcing parts is costly and difficult.

The fault must be within one of three systems: the TCI unit, the ignition power winding, or the high voltage coil pack. I've checked all three, but I'm still stuck as nothing is obviously wrong.

Here’s what I’ve done so far:

1. TCI/CI Unit seems OK
The TCI unit seems to be functioning correctly.  I've probed around and found one faulty diode(replaced) but otherwise all components are OK.

I’ve attached a waveform capture ("trigger&discharge.jpg") for reference:

Green trace: Trigger signal
Yellow trace: Capacitor discharge into the primary winding
The discharge capacitor measures 2181µF, ESR of 0.13Ω, and a Vloss of 0.9%. Based on these values, it seems fine.

I’ve also attached a schematic I created, a picture of the TCI unit, the coil, and the relevant service manual diagram for reference.

2. Ignition Power Winding Voltage seems low
The voltage from the ignition power winding seems a bit low—around 8V peak-to-peak. Can anyone confirm if this is within acceptable limits?

I've attached a photo ("ignition_power_winding.jpg") showing the yellow trace across a 1KΩ resistor.
Could the low voltage be due to the pull-cord start mechanism? I'm only seeing 300V peak-to-peak on the primary when pulling the cord.

3. High Voltage Coil Pack seems OK
The coil, a Taizhoutongtu KG40-141000 is a low-resistance type designed for a capacitive discharge system (not the interrupt-type circuit).
I've searched for more information but not uncovered a datasheet (There's not even a website for Taizhoutongtu?!)

The resistance values I measured match the spec
Primary: 1.3Ω
Secondary: 16kΩ
These resistances suggest a turns ratio of about 1:100, implying a primary voltage of around 150V.

However, I’m only seeing 100V peak-to-peak. Does anyone know if this voltage too low?
I wondered about charging a capacitor using my mains inverter and discharging it into the primary?

(Note: I’ve bypassed all ignition disabling systems for testing and even tried a new spark plug.)

[Dougmc]

I see on the board the diode replace but can't see the reference number.
Which diode was it?
Was it open,shorted,leaky?
Try a new spark plug?

[dial-a-monkey]

Thanks for your reply, the diode (D2) IN4007 SOD-123 had a crack in it that could have been thermal? Yes tried new spark plug My schematic must still have a few errors I'm hoping to resolve.

[CaptDon]

Your schematic can't be correct. Ignition power feeding the pair of diodes as drawn would put negative voltage on one capacitor and positive on the other. (C2/C3) The coil driver circuit doesn't make sense either. You may be able to connect one of the Briggs and Stratton solid state devices made to bypass the original points and condensor system. They work fantastic!!! You have an electronic trigger system but the bulk of the spark energy is still generated by the flywheel magnets building a magnetic field in the coil and then energy being released when the field collapses. McCullough also made after market solid state ignition modules to directly replace the points in their chain saws. Again, they worked fantastic. You simply lifted the wire going to the points/condensor  and connected the solid state module to that wire and also to secured the module to frame ground. I converted a 5HP Briggs on my mini-bike and a Mini-Mac McCullough chain saw. They start on the first pull every time!!!! Most original points ignition McCullough engines need a secret handshake and a blessing from God as well as some starter fluid before they even think about starting!! Many hardware stores and lawnmower shops carried the modules.

[dial-a-monkey]

You're absolutely right—D2 shouldn't have that polarity! But I'm quite sure that's how it was??!!!. There were also some other unusual traces on the board, yes near the main Transistor - a BJT,!! ( identified using a component tester as I couldn't recover the markings after removing the epoxy potting) that said, the schematic definitely needs more work...However, the traces suggest that it does function correctly—or at least, I think it does.🤔?

[CaptDon]

The Briggs kit is #394970 and it may be magnetically triggered as it fits right onto the magneto ignition coil. I remember mounting mine on the pole pieces. However, don't fear, the aftermarket kit for the chainsaw was totally independent and could be mounted anywhere although my engine mechanic buddy suggested to mount it inside the intake plenum on the clean air side of the air filter. I have never been happy with the Honda generators!!!! I have used the Hondas all the way up to their 6KW models in remote broadcasting units and they all sucked!!!! The big ones had the carb fuel overflow directed into the crankcase. The float needle and seat in the carb was trash and the crankcase would fill up with fuel, then when the connecting rod(s) blew right through the side of the crankcase the fire was HUGE!!! After endless repairs I pulled out the 4KW and the 6KW, jammed the throttles wide open and had some laughs watching them self destruct!!!! I hated them!!!

[Dougmc]

There is guy in this group that specializes in coils.
They may also a dedicated group for your unit.
Hopefully you'll get more specs on that coil
And let us know,we all like knowledge
https://groups.io/g/SharingSmallEngineSecrets
Doug

[CaptDon]

The chainsaw module  look up 'ProLine Ignition Module Chip'. I found several on Ebay. Assuming your coil is good I think you may be able to wire one of these modules for use in place of your possibly defective module. it would probably be connected to your 'ignition power' lead and not the trigger lead. I'll have to review your schematic again. Most of the Honda Inverter generators blow up the inverter module which cost more than the unit is worth.

[dial-a-monkey]

Small engines—I have a love-hate relationship with them! Thankfully, I only have to deal with the issues occasionally, but the problems are rarely simple or logical. It's like they’re designed to defy reason and knowledge! ... can relate to the "secret handshake..."