Wiring harness musings

1974jh5

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osteoderm's excellent build thread got me to thinking. The number one problem with old bikes and cars is the electrical stuff is worn and corroded. That means people will patch the harness to keep the bike or car going, that's fine but if not done properly will cause more trouble than the original failure. Sometimes it's necessary to build from scratch, so after building and repairing many harnesses I'm going to lay out what I have learned the hard way, often via the 'let the smoke out' method.

Take a few minutes to really think through how the wires will route, consider things like needing to replace or access something quickly. Will you be using stock components that you may need to replace later (rectifier, ignition switch, etc)?

Also consider (as Yamaha did) running multiple circuits on a single fuse to cut down on the size of the fuse block. I will say that Yamaha did cut some corners, I think these bikes need six fuses instead of four, as in: headlights, brake/tail lights, charging system, ignition system, horn and turn signals. Horns (particularly loud ones) draw a LOT of power, BTW. Yamaha put the horn, brake lights and turn signals all on the same circuit. That means if the horn pops the fuse you also lose the brake lights! Not good.

When choosing connectors for building race car harnesses, I prefer the Weatherpak connectors.They are well engineered and sealed against water intrusion and thus corrosion. Weatherpaks:

512_1418_large.jpg


Unfortunately, IMHO Weatherpaks are too big and bulky for bike use. The molded nylon OE connectors that Mike's sells are decent stuff from an amp draw and voltage drop standpoint, but still a bit bulky.
scdnh4.jpg


Yamaha used them because they are cheap. Sometimes you may need to use them, such as where the stock ignition switch plugs into the harness. If you don't use an OE connector on the harness, you will have to cut/splice/etc if you buy a new OE part. They are also not weather sealed.

The 'bullet' connectors with the silicone sleeves sold by Mike's are very good stuff. We used to use those on RC cars, the voltage drop was surprisingly low and in one test it took ~120 amps at 7.2 volts to cause a failure. Your fuse should blow first! The silicone sleeves are very good at sealing water out.

blackbox10-29-08%20(6).jpg

The winnar for availability and size are those white plastic connectors available at Radio Shack, they are known as Molex connectors. The amp capacity and voltage drop will be sufficient for pretty much anything on these bikes and they are pretty small.

molex.jpg


They are not waterproof, though. When you wash your bike, even the mildest soaps are sort of caustic and will start corrosion. So if you use those connectors, pack the back side with clear silicone sealant. After that dries, use a dab of dielectric grease when you put it together for years of trouble free operation. If you use the OE type connectors, treat them the same way.

If you decide to build your own harness and you don't know how to solder, learn this skill first. Practice on scrap wire etc, learn how to make a good solid soldered connection. Then smear a little dielectric grease on the solder joint and slip some shrink wrap over it for a long lasting waterproof connection. About solder joints: they should always be in a straight and well supported run of wiring, not in a turn or where the joint will flex a lot because that will lead to early failure.

If I catch any of you using Scotchloks I will YELL AT YOU IN CAPS TILL YOU DIE. Please forget those things exist. This is a Scotchlok:
082-100_s.jpg

They slice through the insulation and cannot be sealed well, meaning corrosion. They also 'guillotine' the wire, causing strands to break inside the insulation. I will use them only in a dire emergency to get me home where I can make a proper repair.

While on this subject, these sold at the auto parts store and the big box hardware stores are garbage as well:

Bullet_Type_Insulated_Female_Connectors_380.jpg


They are corrosion prone and the female side has very little 'spring' to it, meaning they do not grip the male part well. Also, that big plastic 'barrel' does not support the wire, making it easy for the wire to flex and break right at the connector.
 
Good stuff. I'm in the planning stages of building my own harness and I was thinking of going with the bullet style with individual watertight fuse holders for the circuits. No signals, so ignition, headlight, taillight, charging and horn.

~ Derek
 
fuck. ive got those bullet connectors all over my bike. i squished the female half a little tighter(loveknot). they dont seem to pull apart very easy. most of them, im sure i could pull the wires rite out before the bullet halves even thought of separating.
i'll keep an eye on them. thanks.
 
Sometimes there is a need for a lot of power to go to something but the switch is not able to accept the load, such as with a high wattage headlight bulb and the stock Yamaha hi/lo beam switch. That's where a 'relay' comes in. Relays are generally considered to be somewhere between smoke/mirrors and voodoo by most folks, they are actually pretty simple. Hopefully the following will demystify it a bit.

The most popular universal type is the Bosch 'ice cube' relay. Like this:

relay.JPG


There's a zillion knockoffs out there. From personal experience, the real Bosch brand are the best. That's about the only thing the Germans build that's not overengineered and expensive as hell to fix. :shrug: I like the ones with the molded in mounting tabs, that makes them easy to mount. Always mount them with the tab pointing up, that keeps water from running into the relay. Bosch seals them pretty well, but mistakes can happen...

It's possible to connect them using only female blade connectors and that will certainly work, but that makes it easy to hook 'em up wrong if you are in a hurry. I'd say spring for the pigtails to keep that from happening:
200-001%20new.jpg


Okay, so how do you wire the damn thing? Bosch numbers their terminals, that makes it pretty easy. Even the knockoffs use the same numbering system.

automotive-relay-relay.gif


So what does this mean? Okay, first: 85 and 86 are what your switch uses to operate the relay. So you need to supply power to either 85 or 86 with your switch, then you ground the other. Such as: your switch supplies power to 85 when turned on and then terminal 86 is grounded to the frame of the bike.

So that leaves 30, 87 and 87a. 30 is power in for your big item. So in the case of our headlight, you would run the fused 12V power to terminal #30. So what happens with 87 and 87a? Here is where you need to be careful. 87a is 'normally hot', that means when power is applied to terminal 30 but the switch has not sent power to 85, terminal 87a is hot. This means terminal 87a MUST NOT be allowed to touch bare metal! So we want the power out to our headlight to be connected to terminal 87. If it's connected to 87a, the headlight will stay on all the time, not what we want.

(By the way, when using this setup for a headlight, hi beam and low beam will each need their own relay. ~OR~ you could wire the low beam to 87a, the high beam to 87, use a main switch in circuit 30, the high beam switch across 85/86 and accomplish this with just one relay. That's getting a bit complicated for our current purposes, though.)

Relay with no power applied to 85/86:
automotive-relay-relayatrest.gif


Now what happens: when the headlight switch is turned on, power goes to 85, through the 'coil' and out to 86. That's drawing maybe 1/2 amp. When the coil is energized, it becomes a magnet and pulls a contact inside the relay closed. This takes power away from 87a and sends it to 87, then your headlight has power.

Relay with power applied to 85/86:

automotive-relay-relayenerg.gif


And that's how a relay works.
 
There is a type of bullet connector that kicks ass. You can find them here. They work perfectly with cloth-covered wire as well as conventional wire. While you're looking, check out the rest of that site... Great folks, super-helpful and easy to deal with, and they make the best custom wire in the country.

Each bullet has a wide end and a narrow end with a small hole. You strip the wire a little long, flux, tin, drop the bullet on the end, and one drop of solder makes it all super-solid. Then trim the protruding end of the bare wire flush with the narrow end of the bullet. The bullet neatly caps the cut insulation, and is bomb-proof.

I've never used the female bullets. Used up bags of the .180 male bullets, connected with the .180 connectors. For semi-permanent connections, I replace the neoprene sleeve with heat-shrink.

I prefer to solder every connection I can. Don't run the wires too tight, and if you ever need to break a connection, you can de-solder or simply cut out the 1/4" of joint.

Otherwise, I like plain ol' boring 1/4" single-crimp spades. I remove the plastic boot, flux/tin/and solder 'em on, then heat-shrink. I heat-shrink the female spade connectors completely, then slit for the male terminal to fit. Cover the whole thing with another layer of heat-shrink.

I like heat-shrink... does it show? :laugh:
 
WTF is a fuse? Why is the aggravating little bastard there?

It's a piece of metal which is carefully shaped and sized so that a given amount of power will cause it to melt. We will use the headlight for an example again: the average headlight filament, high or low beam, will draw around 8 amps. (There's a math formula for this, just take my word for it.) The battery supplies power to the headlight filament through wiring and switches. As long as the power goes from the battery and through the filament, the circuit won't draw more than the 8 amps.

Now if, somewhere along the line, the insulation on the wire gets breached and the conductor inside touches metal on the bike, there is now a 'short circuit', so named because the electricity is taking a 'short cut' back to the ground point and thence to the battery.

The battery is stupid, it doesn't know there is a short so suddenly a LOT of power flows through the wire. The wire is sized for a given amp load. Back to the headlight; it's common practice to size the wire a bit bigger than whatever constant load it will be expected to carry. IIRC 18 ga. wire is good to 20 amps, but in the case of this short there is a LOT more amperage flowing. The wire gets overloaded, gets hot and melts, your headlight quits working and you smell that expensive odor.

If there's a fuse in the circuit, instead of the wire melting and smoking there's a small 'snap' noise as the fuse 'blows'. The fuse is sized to blow at a lower amp draw than the weakest part of the circuit but to be able to supply as much power as the protected item needs. So if our headlight draws 8 amps, the fuse will generally be sized at 10 amps. that keeps it from blowing as soon as the headlight is turned on but also it will blow before something in the circuit gets damaged. That's why it's important to use the same size (amp capacity) fuse as a replacement. If a 10 amp is replaced by a 30 amp, even though there is a fuse it is possible to damage something in the circuit ($$$). That's also why a fuse should never be replaced with wire, tin foil, etc. It's also why a fuse that persistently blows means you need to investigate why. Chasing shorts is for another time, though.

These bikes used the old 'glass tube' type fuse, which were state of the art back then.
GLASS-TUBE-FUSE-5X20-R1002393596.JPG

I hate these damn things. They are prone to something which will drive you nuts: the metal inside will get brittle as it ages and with vibration (no, an XS doesn't shake!) it will break loose from the metal end cap. The fuse will look perfect but won' make a connection. Save yourself some trouble, if you still have these replace them with new ones and keep your sanity. (Remarked the guy who had to reassemble a Dodge dash because his girlfriend's dad did not check the fuse for this type failure befor jumping straight into looking for a nonexistent wiring problem.)

The glass tube types have all but vanished from the car/bike world but are still used in electronic equipment which is not so prone to temperature swings and vibration. Cars and bikes switched to ATC's quite some time back.

atc-fuse__57279_zoom.gif


These are just about impervious to vibration, are weather sealed and color coded for easy amp capacity identification. They won't fit in the stock fuse block, but there are universal blocks that make the switch to these a Saturday afternoon project. I've used this type with great success:

73801.jpg


The latest is what's called the ATM fuse, it's essentially a 2/3 scale ATC fuse. The fuse block takes up much less space. The blocks etc are also smaller thn the glass tube or ATC types, perfect for a bobber where you are trying to keep stuff clean.

24003-24030_LR.jpg
 
Short circuit? What's that and how do I fix it?

The basics of a 12V DC (direct current) electric circuit are the battery (supplies voltage) the wiring (transmits that voltage) switch (how you control when someting turns on or off) the load (bulb, motor, etc).

Everything between the positive side of the battery and the load are considered the power side of the circuit. Everything after the load is considered the ground side.
Power flows from the positive side of the battery through the wiring to the switch, then to the load, then through the load back to the ground side of the wiring and thus back to the battery.

Electricity is like a lot of people we all know; it's lazy and wants to take the easy way out. Sort of like your no 'count cousin. That's why the insulation on wiring is important, that's what keeps the electricity from finding the easy way back to the battery.

A short circuit is when that insulation fails on the positive or power side of the circuit and power finds a quick easy way back to the battery. If insulation fails on the ground side nothing weird will happen because the power has already been through the load.

There is also an 'open circuit'. That's where electricity fails to reach its intended destination but is not shorted out. The two are way different and need different methods to diagnose/repair.

A short is characterized by a fuse which blows. The fuse is doing its job, it's keeping the wiring harness from going up in smoke. So how do you determine where the short is?

Before ripping stuff apart, you need to remember 1) be methodical and 2) don't jump to conclusions.

First thing: you need a wiring diagram. Wires are color coded so that you can easily determine that the wire you are staring at in the rat's nest inside the headlight shell is still the same wire connected to the fuse under the seat that keeps blowing. If you don't have a wiring diagram, don't start working on the bike because you will drive yourself insane. For instance, the brown wire which supplies power for the horn circuit also has two other wires of different colors spliced to it inside the harness and they supply power to other systems in the bike. That's something you need to know before ripping into stuff!

So now that you know what the wire color code is, how do you determine where the short is? First thing: wires rarely if ever fail inside the wrapped part of the harness. In the vast majority of cases, it's at a connector or where wires come out of the wrapping. So that means the first thing to do is look at the connectors for the circuit. If a connector has an old brittle plastic shell which has crumbled, there is a very good chance you have just found your short. Vibration and motion will cause the connector to move and if the bare conductor touches metal, pow there's a short.

Next is insulation worn or rubbed through. The wiring harness runs all over the bike, it has to go in all kinds of odd places. Vibration will cause the harness to rub on the metal frame and other parts. Over a long period, this will eventually allow the conductor inside to touch bare metal and now there's a short. This is common under the fuel tank or where the harness goes through a hole, such as where it goes into the headlight shell. The headlight is a favorite spot for shorts for another reason: as the forks are turned the wiring harness has to flex and just like anything the flexing will either rub through or break the insulation.

In this picture of a Jeep wiring harness, you'll see a green wire and just below it a blue one. The blue wire has a dark spot, that's from arcing. That's what a worn wire generally will look like. This is pretty typical of a harness rubbing against something.
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Flexing will usually leave you something like this:
broken-insulation.jpg

It's pretty easy to see.

In any case, you need to 1) fix the failed insulation 2) see if you can keep it from happening again. Electrical tape is okay as a temporary fix, but it doesn't last and will let water in. Solder and shrink wrap is the way to do it correctly. I have used 'butt splices', but the insulated types are pretty crappy. They take up a lot of room and do not keep water out.
Insulated butt splice:
2156h-outlined.jpg

I prefer the uninsulated types, like this:
SUP-1-091.jpg


and then use shrink wrap over them. FWIW, I have also found that the wire gauge marked on the splice is a bit misleading. For instance, a 14 gauge wire is a snug fit inside a splice for 18-22 gauge.

If your bad wire is in an area where it has to flex such as the headlight shell area, then you don't want a splice in the middle of the flexy part. The splice won't flex and will lead to problems pretty quick. So in this case, you snip out about 6" of the wire, then splice in a new section of wire. That means two splices but in the long run it's worth it.

Any time you see one worn or broken wire, the ones nearby are very likely to have a problem as well. It's a good idea to check them carefully and if you see signs of rubbing or insulation failure go ahead and shrink wrap them too.

Sometimes you don't see a damn thing wrong with the wiring but it still pops fuses. 'Sup with that? Check your switches and the load. Handlebar switches have been known to get corrosion inside, and corrosion can conduct electricity. In fact, water is the #1 enemy of wiring.

The load can be a problem. In the case of a bulb, I have seen an 1156 bulb literally jammed in where an 1157 was supposed to go. They have completely different bases and an 1156 will short out an 1157 socket. And vice versa. The 'pins' on the bulb base are supposed to prevent the wrong bulb from being used in a given socket, but as a friend of mine used to say, 'combine brute force with gross ignorance...' In the event of an electric motor (this is not common on bikes) they can short out due to worn bushings or a bad brush holder.

A poor previous repair is a big cause of shorts. I cannot count the number of times I have looked at a MG or Triumph and found trunk wiring 'repaired' by using speaker wire or that lamp 'zip cord', the splices were just wires twisted together and either not insulated at all or they are wrapped in masking tape or have a wire nut twisted onto the so called splice.

Okay, so you have looked at this stuff and still don't see anything wrong but the fuse still blows. What next?

Grab one of these little dudes:
Circuit%20Breaker%20Blade%20Group.gif.gif

in a 10 amp capacity version. It's a circuit breaker, sort of like a fuse which automatically resets itself when a short quits. Use insulated alligator clips to connect the circuit breaker to the original glass tube fuse holder, if there is a short the breaker will begin clicking. Now you begin methodically testing the circuit; start by wiggling the wiring harness. Then begin unplugging things (bulbs, etc) one at a time and leave them disconnected. When you wiggle or unplug something and the clicking stops, you have found the area of the short. If it was stoped by wiggling the harness, investigate carefully. If the harness looks fine from the outside, keep in mind it is possible that two or more wires inside the harness have rubbed against each other and caused a short inside.

If it's something you unplugged that made it quit clicking, check that part very carefully. The wires going into taillights, turn signals, etc are generally run through plastic tubes. Those tubes can crumble with age, the wires then vibrate/rub the housing and pow, a short. If it's a solid state part like the rectifier, it's very possible it has an internal short but (and this goes back to being methodical and not jumping to conclusions) there is wiring between the rectifier and the alternator which could be the source as well. So check that carefully before condemning the rectifier.
 
here's a littel tester everyone should have,you put in blowing fuse location and if theres a dead short it will light up! start loking around unpluging bulbs plugs what ever you think is shorting if the bulb turns off or dimes (some things have feedback so it might dimly stay on) you now know were to look, solder a small bulb12V on a blown fuse the red 1 is a bit harder but can be dun,
 

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This is a well written piece. Well done. It should help many people in there quest for reliable electrics.
Leo
 
Excellent advice! I'm starting to lay out my "from scratch" harness and just picked up a bunch of Molex connectors & pins. I used these connectors on a work project with great success (the motor controller used them as the interface so I had no choice). Figured they are cheap and readily available so am using them on my bike harness. I am also using a gang type fuse block (hot on one side). Add a fuse to add a circuit ;-)
Thanks for the write ups!
 
I mentioned open circuits earlier. Sometimes people use the term 'short' to describe any sort of electrical failure, but that can lead you down the wrong road. A 'short' is where a wire or etc is grounded to the metal of the chassis causing electricity to take a 'shortcut' back to the battery, this generally results in fuses popping and if the fuse is replaced with something that won't blow it usually results in smoke and/or fire.

An 'open circuit' is where power is not getting to whatever you want to have work. It helps to visualize an open circuit as similar to a blown fuse: power comes into one side of the fuse but since the fuse is blown it can't get to the other side.

As before, start with a wiring diagram. To do otherwise is a sure route to madness. A simple and inexpensive tool which will help a lot is a test light.

test_light.jpg


How it's used:

tsp-550-8.gif


The alligator clip is connected to a ground, then the sharp probe is touched to whatever you need to test. It helps for the probe to be really sharp, since sometimes you need to probe into a wire through the insulation.

Referring to your wiring diagram, start with the fuse block and the ignition must be on. Touch the probe to the fuse block terminals one at a time with the fuse in place. If one terminal lights up and the other doesn't, check that fuse carefully before going any further. Remember, these old glass tube fuses will break internally and look like there is nothing whatsoever wrong with it.

If the fuse is fine, then keep checking as you go up the wiring harness. It's best to check both sides of the connectors, in most cases you will find your open circuit at one of those. As you go up, if the probe keeps lighting up that means you have power that far. When the probe no longer lights up, you are very near the source of the problem.

Let's say you have traced the problem to a connector; when it's plugged in you have power on one side but not the other. Unplug the connector and carefully examine the terminals. You will generally find something wrong, one is bent or etc. Sometimes when you disconnect the connector you will notice that the plastic is brown and has a bubbled appearance around a terminal. That's because it has been hot and started to melt the plastic. A sort of extreme example of this:

mxelbr07a_blower_resistor_Dodge.jpg


What happens is the female terminal does not tightly grip the male terminal, this adds to the resistance across the connector. Whatever the load is in that circuit is still trying to draw the amount of power it needs and the poor connection heats up, just like a stove element. As the metal terminals get hot, the female terminal loses its 'springiness' which causes it to relax its grip which in turn raises the resistance which etc etc etc. (Funny how female stuff is at the root of so much trouble, isn't it? :laugh:) The fix: replace the terminals and the plastic connector housing.

Sometimes a wire will break off at a connector. That's usually because the harness flexes at the connector. The metal wire will 'work harden' and eventually break. Once in a while this will happen inside the wiring harness, that is difficult to track down unless you open the harness up. From previous experience, sometimes it's easiest to just run another wire outside the main harness, bypass what's inside.

You don't see it much in these harnesses but automotive harnesses will have splices inside which are done with brass crimp fittings. That's normally when a wire has to go from a single power wire to a couple of different circuits. The horn/brake/turn signal wires are probably the best example of these bikes, a single wire from the fuse block has two other wires (of different colors, no less) spliced to it inside the harness. That's another reason to be sure you have a wiring diagram.

A real head scratcher sometimes is a wire with corrosion inside it. This happens when water gets into the wire, it sort of 'wicks' its way in. Copper and other metals which conduct electricity are prone to corrosion in the first place, add a little electricity to the trapped water and just watch it go. Examine the wire carefully; if you see that blue-green stuff in the wire at the connector it's like an iceberg, you are only seeing the tip of the problem. The real problem is further back in the harness. Like this:

004.jpg


Sometimes it looks like this:

wire_corrosion.JPG


In this case, the corrosion will not conduct electricity as well as real live copper wire. It may conduct a very small amount, and that's why sometimes using a multimeter instead of a test light will lead you the wrong way. It's entirely possible to check a connector with a multimeter and it shows battery voltage but your load still does not work. Why? It might be 12 volts but only 1/10 amp, which is not enough to run the load. It also won't run your test light, which is why I prefer using a test light to trace an open circuit.

Switches can be another open circuit source. The terminals can get corroded or dirty and not conduct electricity, that's usually worst on something that's been sitting a long time (like a 'ran when parked' barn find XS). In this case your test light will show power going into the switch and nothing coming out. Generally that's a case of squirting some sort of penetrant into the switch, then working it back and forth or however it goes several times, then check it again.

On old switches which carry a lot of electrical load (think ignition switch), the contacts which are made into the plastic can get hot from a high amp draw. That melts the plastic which causes the terminal to sink into the plastic and quit making contact. That may not be readily apparent, it might require some very close examination on the part of the guy checking it out.

columswitch1.jpg


This is one reason to use a relay for a big electrical load, that way it's taken off the switch and put on the relay's terminals.
 
Thanks for the positive comments, guys. I'm sure I will think of more stuff, as I do I'll try to add to this.

By the way, about the link osteoderm posted for the bullet terminals: those are excellent stuff. The funny part is they are a dead ringer for the 'Lucar' connectors used in British cars right up till around 1982 or so, and ask any Britmobile fanatic how good those were. :laugh: The ones made now have much higher quality metal compared to the old stuff.
 
Great thread and very timely for me as it has motivated me to get out and start building my wire harness since I can't really do any mech work on my build right now.

Cheers for the help
 
I love my test light! the malti-meter does the same thing but the test light adds a bit of current, example if you have bad wire broken off at a terminal but 1 strand is still in tacked or you have a plug like the pic on top, the meter would show good voltage (ex:12+V) as soon you put a test light on you might get no or a dim light telling you theirs something is wrong, and don't get the led test light they don't draw that much current so 5v or 12v is the same thing for led test light, and learn the bulbs (brightness) light if you probe wires and it's dimmer then norm. Something is cooking! As for probing you’re making small holes in the wires that can corrode! as for the test light put a heat shrink body of needle about 1/4 exposed from the tip this way if you touch metal (accidentally) at the same time tip is 12v you don't get a short and back the wire up with something not your finger you'll be probing your blood type! and if you get brave and want to tackle your 2011 F-150 with a test light don't!! Electronics don't like them!
 
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speez makes a good point. Newer cars with CAN-BUS systems do not take kindly to being probed with a test light. There's a thing called a 'logic probe' that can be used in those situations.

dp-21.jpg


It's definitely one of those things where you really need to know exactly what you are probing before going nuts with it. I have very little experience with them.
 
Soldering is one of those voodoo things also, but it's actually pretty simple.

A quick soldering tutorial: first, you need an iron. I prefer irons to those trigger guns, the guns are heavy and hard to use around tight areas.

aefe5a86-71e2-4af7-a6aa-513b908555ae_400.jpg


There's a lot of debate about how much iron to get. For soldering wires I prefer a 40 watt iron. Here's why: once you begin soldering a wire it sucks a LOT of heat from the iron. A 20 watt iron struggles to keep up and that is much worse when using heat sinks (more on that later) or in cold weather. That means you have to keep the iron on your work much longer and that can lead to melted insulation and just a generally sloppy looking job. So a 40 watt is ideal.

Now once you get to tinkering with circuit boards, a 20 watt is perfect. So you may want to go ahead and get both, they are pretty inexpensive.

I refer to wire gauge, that's AWG or American Wire Gauge. The bigger the number the smaller the wire. (That's stupid, isn't it? 0000 gauge is some MONSTROUS stuff.) The average XS uses 20, 18, 16 and 14 gauge depending on what they go to.

You need a stand for the iron, they are easy to make and some of the kits at Radio Shack include a little stamped one which is adequate but that's about it. I have an old stand from an Ungar 'soldering station', it looks something like this and it's great.

R431413-01.jpg


The sponge is for wiping the iron. It needs to be wet before you start on your project.

You need solder; it needs to be rosin core. Solid solder is more of a radiator repair thing, it requires a 'flux' be used to clean the metal you are soldering and to me that's just an extra unecessary step. Acid core will lead to corrosion, not to mention it can 'pop' and spit back in your face. Acid core is more of a plumbing thing anyway.

For wires etc thin rosin core solder is best. You need a good set of wire strippers and it helps to have a couple pairs of hemostats, like you used in your pothead daze.

Before you prep your wires, plug the iron in. It takes a few minutes for it to get hot enough. While it's heating, do your wire prep.

Start by stripping the wires (duh). Solder is great stuff and reasonably strong, but for best results the wires should be twisted together. It takes a little practice, but you want something like this:
Step-3.jpg


That means you need to strip the wires accordingly. About an inch on each wire is OK on wires up to 16 gauge, over that you want about an inch and a quarter stripped on each wire.

But before you twist the wires together, you need to get your shrink wrap tube on the wire. Cut the shrink wrap about an inch longer than the bare splice, then slide it up one of the wires as far as you can. That's so the heat of soldering does not make the shrink wrap shrink prematurely (that's the same thing women get pissed over. Oops, is this thing on?).

Once the shrink wrap is in place, now twist the wires together. This might be a PITA to hold them together, sometimes the weight of the wires wants to keep yanking them apart if the harness is still on the bike. Tape the wire to something solid temporarily.

I mentioned hemostats and heat sinks earlier. They are one and the same. On wires up to about 18 gauge, the heat sinks are generally not needed because the iron will heat the thin wire so quickly you won't have to worry about melting insulation or having the heat shrink do its thing early. 16-14-12 gauge, yeah I want heat sinks. Create a heat sink by lightly clamping the hemostat to the copper wire right where the einsulation ends, one on each end of the splice.

Now touch the solder to the tip of the iron. It should melt instantly and flow out evenly on the tip of the iron. If it doesn't do this, the iron is not hot enough and you need to find something to do for a minute like get a beer.

Once the iron is hot enough, take the ironin one hand and the solder in the other. Touch the tip of the iron to the center of your twisted wires, wait abiut 3 seconds, then touch the solder to the wire right next to the iron, It should melt instantly when it touches the wire.

Note that this is the secret to soldering; your work piece needs to be hot enough to melt the solder. As the solder melts, 'feed' it into the splice and you should be able to see the solder 'wick' into the wire. This shouldn't take more than a few seconds. Once the splice is covered with solder, take the iron off immediately and wait for it to cool. Don't use too much solder. This all takes a little practice, that's why I recommend first practicing on some stray scraps of wire till you are comfortable with the whole thing.

A properly done solder joint will conform to the wire strands. It should look like this:

Done.jpg


Let the solder cool completely, that will take a few minutes. If you used them, take the heat sinks off, then smear a little dielectric grease on the splice. Slide the shrink wrap over the splice, hit it with a hot air gun/blow dryer/cigarette lighter so it clamps down on the wire and you are done.

Soldering takes longer than just jamming wires into a butt splice and crimping, but it's a neater looking job, has less voltage drop and much less likely to fail due to water intrusion than a butt splice. Plus, it's a cool thing to be able to do in front of your less than gearhead friends, almost as cool as welding. :wink2:
 
Soldering a ring or other type terminal to the end of a wire is a good thing. There are some technique differences.

Start with an uninsulated wire terminal. Like this:

1017h-outlined.jpg


Strip the wire end so it can go all the way through the 'barrel' of the terminal and stick out maybe 1/16 inch past it. Then slide a piece of shrink wrap, maybe 1 1/4" long, up the wire, then slide the terminal onto the wire.

See the split in the barrel? I use that to my advantage. Use a regular pair of pliers, set the tip of the jaw next to the split and then squeeze till it's crimped. Now turn the pliers 90 degrees and squeeze the barrel from the sides till the other uncrimed side slides over the crimped one. Now put the pliers so the jaws cover both pieces and squeeze the snot out of them. Makes a nice neat looking crimp.

Clamp the wire with your hemostats and position it so the terminal is pointing up. Take the preheated iron in one hand and the solder in the other. Put the iron on the barrel of the terminal and give it a few seconds, maybe 5-8 since you are heating that big old terminal, then touch the solder to the wire sticking out of the barrel. It should melt almost instantly. If it doesn't, take the solder off, wait a few more seconds then touch it to the wire again.

Oce the solder begins to melt, it will run down inside the barrel. Watch till it 'fills' the barrel, then take the iron and solder off immediately. Wait a short time, then take the hemostats off too. Don't slide the shrink wrap up just yet, the terminal will stay pretty hot for probably 3-4 minutes. Once cooled, slide the shrink wrap up as far as it will go and hit it with the hot air gun etc.

On female blade terminals, cut the shrink wrap about a half inch longer, slide it all the way up to the opening of the terminal, then hit it with the heat gun. It should look like this when done:

P2130014A.jpg
 
About shrink wrap: not only does it insulate and waterproof a connector but it also adds support to a wire, which is a big help in a wiring harness. Plus, it just looks so professional.
 
vintageconnections.com is a great source for the bullet connectors, various connectors for most old jap bikes, Yamaha in particular, and they have nice jap style sleeving by the foot in several sizes-good for custom a must for restoration.

Good thread.

John
 
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