Honda CG 125 Indicator Relay Issue

[rego21]

Hi all,

I’m "rebuilding" a Honda CG 125 from 1992. When the motorcycle is stall, I can see that the indicators are flashing as expected. However, when I kickstart it the indicator stay stall (no flashing at all) and the relay seems to be gone because when I turn off the motorcycle again and test the indicators they stay stall. Anyone have any idea what the issue could be? Thanks!

[stinkwheel]

Old electromechanical indicator relays are sensitive to the load on the circuit. If the bulbs are the incorrect wattage, it will not flash correctly (or will flash too fast). If the voltage supply is incorrect, you can have similar issues.

I'd replace it with an electronic flasher relay anyway which will flash at the same speed regardless of what else is going on. It may be showing you have a charging issue or a dead/dying battery which would also be worth testing.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[rego21]

Thanks @stinkwheel for the reply. I replaced the relay with a electronic flasher from Aliexpress - a 2 pin one with support for 12v. Like I mentioned it works ok when I don’t kickstarter the motorcycle, just turn the ignition key on and test the indicators everything ok. I believe probably there is a current spike when I kickstarter and the relay burns ( I checked the voltage and seems ok it stays at 7-8v). Could be a ground issue?

[stinkwheel]

An earth problem is certainly something to investigate. I presume it's a 6v electrical system?

It might also be that the rectifier has failed and is putting out AC instead of DC or an excessive voltage. Is your 7-8v across the battery with the engine running?

EDIT: I think your bike is 12v so where is the 7-8V reading coming from? It's not right.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[rego21]

[rego21]

[stinkwheel]

You aren't going to get stable and sufficient DC out of that charging system without a battery. It'll run the lights fine because they are on direct AC and as you correctly pointed out, the ignition self-excites.

You have no chance of it running the flashers/brake light/horn direct without a battery, a capacitor or a special reg/rec. Even then, they don't really generate enough power directly to light up the incandescants, they rely on the battery storing power and it being used intermittantly.

TL;DR. You need a battery.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[rego21]

[jeffyjeff]

[rego21]

[jeffyjeff]

I beg your pardon for jumping to the wrong conclusion.
____________________
History shows again and again how nature points out the folly of men - BOC

[stinkwheel]

I think the 1992 will be a Brazilian model which has two coils on the stator.

One of them provides power for the spark, this is a totally seperate system and has nothing to do with the lighting or accessories. So a running engine tells you nothing about the rest of the electrical system.

The other coil is split in half. When the lights are off, the two halves feed into a basic regulator rectifier which gives a very dirty 12V DC output to the battery. When the lights are on, one half of the coil feeds AC power directly to the lights. The other half feeds even dirtier and less power to the battery. Almost certainly not enough power to light up the brake light and indicators together.

It's a cheap and nasty charging system designed to store enough power in the battery to make the flashers and tail light work when they are needed. It's also basic and reliable if it's used as intended and the seperate ignition coil means it's unlikely to leave you stranded at the side of the road with no spark, even if all the rest of the electrics fail.

I've been trying to make a similar but slightly more refined system work without a battery on my current project bike, I've been using capacitors to do the job of the battery. I haven't been able to get it to work reliably and it's cooked two stators so far. Attempt three is going to be me giving up on the idea and fitting a battery.

I also have two dead flasher relays.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[rego21]

[stinkwheel]

[rego21]

[rego21]

Hi again,

I will also try to revive the initial topic discussion.

So I tested the stator (with motorcycle off) and seems to be ok:
Yellow to White resistance is 0.8
White to Ground is 0.8
Yellow is shorted to ground, which I think its normal when the motorcycle is off since this wire is responsible for the front and back light

What Im missing to test is the rectifier which is under the tank and Im trying to avoid to remove it.

My doubt still is, how the indicators, horn and brake light can work when the motorcycle is on ? Can a faulty rectifier power this components ? Or even when faulty it should only put AC at the battery plugs or none at all ?

[stinkwheel]

It's probably working fine, but it's single phase so it's only giving you a single, half-rectified and truncated waveform. More modern bikes have a three phase output with the phases overlapping.

So the output from yours will look like this, you aren't getting a constant voltage:
https://ctlsys.com/wp-content/uploads/2016/10/Positive-Half-Cycles.png

The output from a modern bike with a three phase output will look more like this:
https://media.geeksforgeeks.org/wp-content/uploads/20231114113858/threephasedrawio-(3).png
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[rego21]

[stinkwheel]

[rego21]

[stinkwheel]

That's right, except the head and tail light are running on AC directly from the stator on a seperate set of wiring and so only work when the engine is running even if you do have a battery. So what you have now is how it's set up to be.

Only the flashers, brake light, horn and warning lights work from the DC side. I'd imagine you probably need to rev it quite hard to make the horn sound like anything other than a strangled duck with no battery which shows how little output there is.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[rego21]

[Easy-X]

[rego21]

[stinkwheel]

Probably. I have no experience of lithium batteries on that type of charging system so not sure how well it will play. Others might know more.

This is the smallest more conventional lead acid I've been able to find.
https://www.tayna.co.uk/motorcycle-batteries/powerline/ytx4l-bs/
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.