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No spark Honda CG125

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Hope someone can help me.

I have a old 6v cg125 with points ignition I am restoring. It had no spark so changed points and then had good spark at plug. Had to remove barrel as had no compression. No its re assembled I have no spark at plug. Have 6 v at the black white cable from generator . Have tried several coils . It seems to be problem since removing brackets which mount to frame which steady top of engine.

Have checked good earth at ignition coil mounting bracket.

Am stumped !!!!!

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Thanks for the reply.

Have set the points to correct gap and get 6v from the black /white wire. The black/white wire will spark on the rocker cover and the bracket for the ignition coil. Don’t have a ignition switch fitted so that cant be shorting out.

Before i removed the valve cover and barrel I had a strong spark !!!

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Sorry had to create new account as couldn’t get in !!

I dont think it had a earth wire from engine to frame and yes it does have a condenser on the ignition coil.


I can fix it! Send me a message and I will sort the accounts out

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Yes and think its ok. Regardless of when the 6v is created timing wise to coincide with the piston. I definitely have 6v at the connection where the black/white wire connects to the yellow wire to the ignition coil. If I hold the black/white wire to the head it will create a strong spark when kicked over.

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Rightyho, take it its not a OEM part like this one then


and if that coloured wire comes from the coil and condenser then it must be valid with the make, have you tried Primary and Secondary tests on the coil and HT Lead

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Hi. First of all thanks for your help.

Yep have tried with spark plugs and tried with plug cap removed just using bare ht wire.

I am a mechanical fitter by trade but this one has me stumped !!

It seems like the voltage is lost when connecting to the ignition coil as if its being grounded out !!!

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no problem matey, would like to get to the bottom of it, so I take it there's no Battery on the bike and you dont have an Ignition switch, so looks like could be wiring and Earthing problem ,with only the Black/White wire coming from the Gen ,6v at the coil/condenser , and you have tried 3 other coils ,there doesnt appear to be a return to Earth, how about looking through the Earth connectors to see if you have a problem there, havent got a pdf manual for this but I do have a paper one , so can grab some pages for you and send pdf if needed

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I dont think there are any earth connectors. I think the earth for the generator is via the backplate in the engine. The earth between the engine and the frame is via the engine top steady.

If it was a earth problem then I would not get a spark from the black/white wire when putting it near the spark plug hole and kicking bike over !!!

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