Question about soldering?

Ran into a problem last night trying to repair the part of the wiring harness that goes from the headlight housing up to the illumination bulbs in the speedometer. Those bulbs haven't been working since I got the bike. I discovered that the wire was broken in the harness where it is crimped together so it can split and got to both bulbs. So I figured well I'll solder that sucker and use heat shrink tubing and it'll be better than new.

Well I couldn't get the solder to stick to the wires?:huh: So I grab a couple brand new strands of wire and try soldering them together. Everything works perfect, wire tins the way it's supposed to, it's a thing of beauty!

Ok, now I'm thinking well the wires look almost black, must be some kind of corrosion on them, keeping them from accepting the solder. I try scraping it off. I try carb cleaner. I try everything I can think of. Solder no stick!:S

Did Kawasaki use some kind of weird non solderable wire back in 1983? Or am I just going insane again?:blink:

Forgot to mention: I did use flux, solder specifically for electrical, and was using a torch. The same method I've used for years when soldering wire connections on my cars and trucks.

Post edited by: Bud1, at: 2005/10/23 12:32

The black coat your talking about is just oxidation, if you can sandpaper the wires just a bit and find clean copper it should take the solder, if not just replace the wires with new close to the same gauge.

yep, sandpaper is the answer

I cut the harness and soldered to put a 78 right hand switch pod on my 80 750 twin, just because I wanted the on/off switch for the lights.

Ok I'll have try that. Would electrical contact cleaner help? That's the one thing I didn't have on hand last night.

most of the contact cleaners leave a residue, bad sp, needs to have the sandpaper used on it,

Ah! I didn't know about the residue part. Thanks!

I dunno if you've corrected the problem or not as yet. If you have, this information will have to wait until the next time

You can solder the most corroded wire in the world, as long as the strands can be cleaned adequately to expose fresh copper.

Here's how: Strip back the wire until you have about 1/2 inch of conductor exposed. Fan the strands out flat on a block of wood, and use a pencil eraser to remove the oxidized material, dragging the eraser out and away from the insulator. Once you see shiny metal, flip the wire over and clean the other side.

Twist the strands back into a wire.

Dip the newly cleaned conductor into soldering flux, and secure it with something (wrap it in cloth and *gently* tighten a vice grip on it, if it's on your bike - otherwise use a bench vice).

NOTE: Do *not* use plumber's flux. This contains acids that will attack the copper and ruin the connection.

Get a soldering iron (or gun). Ensure the tip is clean and is well 'wetted' with a small blob of liquid solder. Apply the wet tip of the soldering iron to the wire. The flux will start smoking and that process will remove the remaining oxidation.

Now, while it's still hot, feed a little solder onto the wire (Do *not* melt the solder with the soldering iron tip!). Use the heat of the wire to melt the solder. Just use enough solder to 'wet' the entire exposed portion of the wire, then remove the soldering iron from the wire before the insulation starts to get damaged by the heat. Allow the wire to cool and the solder to solidify. This process is called "tinning" the wire.

Repeat with the other wire. You may need to add a length of jumper wire if trimming your original wire leaves you short. Tin the ends of this jumper wire if used, as well.

Important! Slip a piece of heat-shrink tubing onto one or the other wire (two pieces of heat-shrink if you used a jumper)

Now lay the tinned parts of your two wires with the conductors overlapping and touching. Apply the soldering iron until the solder melts. Add a little solder, again using the wires to melt it. Remove the heat, and hold the wires *very* still until the solder solidifies. If you move before it cools, you'll get a 'cold joint' that will be mechanically weak and electrically questionable. If that happens, re-heat and apply a little more solder. The freshly soldered joint should look shiny, with no blobs of excess solder.

With an hour of practice you'll be doing it like a pro! Better yet, if you spend that hour, it's a critical skill that you'll find very handy throughout your life, and not just on motorbikes.

Best wishes,
Mark (a navy electrician in a previous life)

Lots of good tips in this thread. I personally wouldn't want any wiring on my bike that had developed oxidation. Cut the wire out and find good wire to solder to. Use rosin core fine gauge solder and heat shrink. Don't both using flux... Hold the solder on top the work and heat from the bottom till the solder flows THROUGH the work else you will have a cold solder joint that will fail. Keep your heat shrink far away from the work till everything has cooled.

Thanks for all the tips and techniques. I've been soldering wires for a long time. Just haven't come across a case of oxidation this bad before. Had me puzzled for awhile. Plus I'm getting a little older and they say the memory is the first to go. I'd heard of the pencil eraser trick before but had forgotten it. :huh:

I have to agree with WG. That much oxidation leaves me concerned about it. I kept cutting the wire further and further away from the break until I had just enough left to use a crimp on connector. (I hate using them!) The wire was black the entire length. Guess I'll check out the rest of the wiring on the bike and replace what I need to this winter along with everything else.

Oh well! without projects life would be boring!:woohoo: