Wires from alternator to regulator

[graybriggs]

I had the three yellow wires burn and melt the insulating cover (one wire completely burnt itself in two) that go from the alternator into the regulator. I have a new heavy-duty regulator now and looking to replace the sections of wire that have burnt out.

Question: is there any specific type/grade of wire I should be using for it to handle the voltage/ampage so there's no chance it'll melt again?

I'm going to reconnect the wires by twising them together, then blob of solder, then wrap joint with insulating tape. Wise? Any electricians tips?

Also any idea what could cause this to happen apart from a knackered regulator? The melting happened only just before the regulator - like 10 cm of the wire that comes out of the regulator. Like some bottleneck is happening. It botheres me that it could be something else such as too much current from alternator?

Lots of questions I know

Cheers!

[AliasOmega]

I would remove the RHS middle panel, and inspect the block of generator connectors. You will probably find this has melted too.

In short, the wires run as follows..

Generator (LH side by your toes) --> out of the casing --> through the engine bay under the carbs --> to a connector block not far from the dip-stick --> through the loom to the rectifier.

I have 10p on the connector block has melted, and therefore i would replace the generator, and wire in another loom tie-wrapped to the existing loom to the rectifier.

[Cammo]

I would also take a good close look at the condition of the connector that goes onto the reg/rec.

Any charred or burnt connectors there will cause problems in the future. You can get new aftermarket plugs, or you can also buy both sized spade connectors from good electrical component shops, just solder new ones in line. You don't need a plug but it's a good diea to waterproof the area with tape, silicon or whatever.

Your wiring techniques sounds solid.

[theonefromthesky]

Chances are the regulator caused the problem, it would most likely have developed a short drawing a huge amount of current thus melting said wires. Replacing the unit with a good one will almost certainly solve the problem. As has been said, I would check all wires back to the generator and make sure that they are ok and all connectors as well (on a side note if you need original connectors, I have a whole bunch of spare ones from a loom that I could send you if you need them). Also, check the windings of the generator, there should be NO continuity between any of the three yellow wires and ground and yellow to yellow wire should measure between 0.1 and 1 ohm, if this differs, replace the generator too.

Replace the wire with more of the same grade, no thicker is required. In the absence of any automotive wire, 240v twin and earth flex is aproximatly the same size, if not slightly bigger and will work perfectly well.

As for soldering you may have issues with some of the cables, on bikes this old the copper core tends to turn black and almost impossible to solder. You will need to gently scratch off this corrosion and use a good quality flux, plumming flux is good. As for the joints, strip back 5mm of both ends to be connected and tin the copper, then get some heat shrink and slide over one side gently solder your two tinned ends together and then slide your heat shrink over the joint and heat until its tight.

Also, when soldering a few wires at the same spot, dont. Cut the wires to be soldered so they are staggered, that way you dont end up with a giant ball of solder joints in one place.


Jody

[wullvfr]

the alternator can show up good resistance and continuity checks even when its past its best.........mine showed up hunky dory results but when i did the voltage output test it was less than satisfactory and when removed,it was very badly burnt out.



william

[Neosophist]

as wullvfr said, they can test 'ok' with a meter and fail under load unless you have a load based tester.

probs usually start off with a knckered battery, they don't take a charge as well, this causes the reg/rec to dump the excess juice as heat, the reg/reg then burns out, fries the altenator and you have 3 dead parts instead of just the battery!