Yamaha Aerox headlight problem

[jondoe]

Hello guys and girls, I'm hoping I can pick the brains of some Aerox owners and/or any electrically skilled people please!

I've inherited an Aerox 100cc, it's a 2000 model, it's had a hard life. Currently everything thing works on the bike apart from the headlights. I've spent some time looking into this and none the wiser, I had some panels off today and tested the lighting coils, they are in spec, testing them for AC output while it's running and it puts out plenty of power.

I can make the headlights function is by running a bodge wire directly from the headlamp earth to anywhere on the stator housing area, high and low beam work, they turn on and off and do as expected. Of course, a bodge wire isn't a repair I suspect there is an AC earthing issue based on that result, but I can't for the life of me figure out where the earths are, the service manual isn't very helpful on that one.

The only other symptom the bike manifests is what feels like AC in the levers, if you rev it up, it tingles a little more!

Happy to take suggestions that don't include setting fire to in a disused quarry

[Nobby the Bastard]

[jondoe]

I started this odyssey suspecting the stator was a gonna, I'd tested it with a multi meter and found it out of spec. One second hand stator later I realised my multi meter was over reading the resistance.... one fluke meter later I found the existing stator is fine resistance wise and is well within the service manual spec, as is the running voltage output.

As far as I can tell the rear and front lights are AC, but indicators, charging, instruments, etc, is DC. Running an earth wire directly to the battery didn't have the desired effect. The stator grounds to itself to the block so my wild assumption here is that this isn't grounded to the frame anymore, but I've no idea where it's meant to ground, nor can I see any broken earthing straps or wiring.

Crossing my fingers someone might know so I don't have to strip all the plastics off on witch hunt for an earth that might not exist

[Nobby the Bastard]

[WD Forte]

RTFM
https://zsebog.com/wp-content/uploads/yamaha-yq100-2000-en.pdf
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bikers smell of wee

[Nobby the Bastard]

[jondoe]

I'm hoping I can find where it was earthed originally and not fudging it just to make it work, that said I may have too. I have RTFM, that's where I got the specs for the stator. No damn mention of an earth strap anywhere I could find, might be missing it though!

I probably need to lift out the seat box next time the weathers good to see what wires are hiding under it.

[Nobby the Bastard]

[Luckyfish13]

[Nobby the Bastard]

[Luckyfish13]

[jondoe]

I first suspected the stator as the problem appeared to only be a lighting issue on the AC side, had the coils broken this would have left me on a similar state, this is detailed in the fault finding section of the service manual so I went down that rabbit hole when my meter was reading a good 0.7 over the maximum, but that turned out to be a red herring.

The electric starter has long been removed so it's kick start only, that said it starts on the first kick and idles fine. With a bodge wire the lamp is as bright as to be expected.

I suppose the ignition works because the spark and the earth are all contained within the block? Where as the lamps AC have to travel down the wiring loom and without a path back there's no circuit.

At times like this I wish I had a garage to work in

[Luckyfish13]

What happens at high revs? At least 7-8k...

Also get ur multimeter out, and do a continuity check between the battery negative terminal and the point on the stator cover where you bodged a wire and the headlights worked fine....if you get me?
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Daytona 650
XT 125R

[jondoe]

I haven't rev'd it up that high, I didn't have a stand to lift the back wheel up so it only got a light rev with the front brake held on with the wheel on some wet grass

Luckyfish13 I see what you're saying, I'll give that a look when I've got some day light and favorable weather, this has so far only been a weekend project :/

[Nobby the Bastard]

[jondoe]

They do indeed share a black wire for an earth. It disappears off into the main loom pretty quickly so I couldn't see if it shares the same earthing point or if it's directly connected.

If it were the regulator and it was shorting straight to earth that might well cause a problem. Would the bodge wire not work though in that instance? The regulator is still in circuit after all.

I did check the connections to it when I found it, I'll add it it to my closer inspection list.

[Luckyfish13]

On the diagram, anything with a -B- earth is wired direct to battery by black cable, the frame earths are shown by the ||| earth symbol...
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Daytona 650
XT 125R

[smegballs]

AC lighting with a "resistor" to pull down the voltage to acceptable levels when headlights not on

Do Not Want

OP how's about you find a RR of a 125 or similar that is designed to rectify/regulate all of the alternators output, feed the headlight from an ign controlled live (poss via relay) and jobs a good un.

Doctor Smegs surgical recommendations are here:

https://i.imgur.com/tJPxuqx.png

That said I've been hacking around with motorcycle electrics for 10+years and I play with soldering irons and heatshrink for funsies, so I'm pretty confident butchering my way thru a wiring loom.

[jondoe]

That's certainly a creative solution to the problem, that's a step up from a bodge wire.

If I were keeping this bike, I'd fudge it to high heaven and take my own poor workmanship on the chin, but, I intend to make it road worthy and sell it on, therefore a proper repair is more desirable for my conscience.

I've found an Aerox earth strap for sale on the web, as a spare part for the 50cc model (although it's NO WHERE on the part diagrams). This makes me think there must be one hiding some where on the 100cc as they are very similar

[smegballs]

The way I see it, putting some piss-weak R/R and using a resistor to soak up excess power is just a cost-cutting exercise by the manufacturer.

My suggestion is a legit improvement over the bargain-basement stock system, if you are gonna be flogging it on tho I can understand keeping it stock.

[Luckyfish13]

[jondoe]

Like a zombie, this tread is coming back from the dead!

January and February flew past in a blink of an eye and the bike sat under it's cover at the end of the garden gently dripping oil onto the concrete, waiting for the day I could be arsed to tinker and the weather was up to scratch...

Today was that day. First the seat came off, then the box, some more plastic trim and the glorious mess of butchered wiring was there to behold. After some considered poking about with the multi-meter and some temporary bodge wires it became apparent that the cause of the lack of AC earth was down to the fact someone had removed the starter motor and removed the shared earth. I found it entombed in half a roll of insulation tape, tucked under the carb .

The bike had been in for a kick start repair before I got my hands on it, they had welded the lever on and said it would require considerable parts to fix "properly" which having looked over the service manual is bull shit of the highest order, but I digress.

The earth ring connector was freed from the tape, cleaned and connected to a suitable earth point that had a screw the same size, lo and behold, the lights worked perfectly.

I can't seem to get attachments working, so page 34 in the service manual shows the looped back earth connection on the start motor itself.

[Nobby the Bastard]

[jondoe]

[Nobby the Bastard]