Honda H100A - Electrical Help (Please)

[eugeroic]

Okay I got this as a barn find project.  Finally have time and funds to start on it.  Never worked on anything like this but so far its has been fun and relatively simple as I had hoped for a first timer (replaced a completely seized clutch).

 

To save any pre-amble, the previous owner stated no spark on the listing, which i figured would be a relatively simple fix (may have been wrong there).  I have bought a new battery, ignition coil and HT lead.  Heres where i need help.  I don’t even know if the previous owner fitted the new ignition switch correctly, and i need a way of testing it, but i cant for the life of me figure out how to do so.

 

To clarify, the bike came with the wiring loom pretty much entirely separate from the frame/engine, it has no bulbs or switches at all, other than the ignition.  Given the current state of it, the project could be dead entirely unless i figure this out.

 

Any help would be hugely appreciated.  Feel free to call me an idiot if I'm missing the obvious, I have been working on it for about 7 hours today.

 

Thanks

[JRH]

Hi @eugeroic and welcome. Why not pop into newbies and introduce yourself.

Sounds like you need a Haynes manual to help. But in the mean time an electrical diagram may help you.

 

Edited April 16, 2024 by JRH

[RideWithStyles]

Hi and Welcome.

 

 

Edited May 14, 2024 by RideWithStyles

[eugeroic]

@JRH Thanks for the quick reply and thanks for the wiring diagram, I do already have it but it's good to know I started looking in the right place at least!

@RideWithStyles This was abandoned and left to rot, if I can even get it idling I'll be chuffed to bits!  Just trying to find out how I can see if the new ignition is even allowing power to the other electrics if you get me.

 

If either of you can tell me what the key is on the wiring diagram that would be great.  Not sure what "IG", "E", "HO", "C1" "TL", "P", "HO1" is.  An educated guess would be IG is ignition, E would be earth?, HO would be horn.  No idea on the rest though.  I did try googling it but don't think I'm asking the right question...

 

Honestly didn't expect replies so quickly but again the help is hugely appreciated.  I'll post on the newbies forum now!

[Tinkicker]

Red wire is permanantly live from battery to ignition switch.

Black is switched live, only live when ignition is on. The battery does not feed the CDI module.

 

The generator feeds the CDI directly, not through the ignition switch.  Soon as you kick it, the CDI is getting power.

 

The bike cannot start with ignition off, because the black and white wire from the CDI is connected to the green ground wire within the switch when it is off.  The CDI capacitor within is therefore grounded and cannot build up a charge to send to the ignition coil despite it getting power from the generator.

 

 

Disconnect the black and white at the switch and you should have spark regardless of the other wires to the switch.  If not, the fault is elsewhere.

Edited April 16, 2024 by Tinkicker

[RideWithStyles]

I

Edited May 14, 2024 by RideWithStyles

[eugeroic]

@Tinkicker Great tip thanks for this, I'll give this a shot tomorrow!

 

@RideWithStyles Thanks for this too, funnily enough I just had a breakthrough after typing out my previous reply and manged to get the horn working by connecting the horn switch directly to the earth that would normally lead to the flywheel.  So at least if nothing else, I've proved the ignition is in-fact working as it should be.  One step closer.

[eugeroic]

20 hours ago, Tinkicker said:

Red wire is permanantly live from battery to ignition switch.

Black is switched live, only live when ignition is on. The battery does not feed the CDI module.

 

The generator feeds the CDI directly, not through the ignition switch.  Soon as you kick it, the CDI is getting power.

 

The bike cannot start with ignition off, because the black and white wire from the CDI is connected to the green ground wire within the switch when it is off.  The CDI capacitor within is therefore grounded and cannot build up a charge to send to the ignition coil despite it getting power from the generator.

 

 

Disconnect the black and white at the switch and you should have spark regardless of the other wires to the switch.  If not, the fault is elsewhere.

This was actually a massive help, I ended up putting a multimeter where the ignition coil would normally be, and used the kick start to spin the flywheel and it had a charge when I disconnected the CDI and when it was connected to the ignition whilst it was on.  But didn’t pass a charge when the ignition was off.  So I’m pretty sure the fault now lies with the ignition coil.

 

Hugely appreciate the help.