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Can anyone tell me the gauge of the wiring from the switches to the connectors inside the headlight?
 

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I just used 20 for all, based on the meancycles kit offered. I really don't feel like redoing all my pretty wiring, but I know there was a few thicker ones in there.
 

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I just remeasured all... My results show the majority of wires at 20gauge with 1 or 2 wires on each side being 18 gauge. Most are 0.036inch conductors, with the larger being around 0.04.

I'm just going to leave it. Nothing says chopper like mismatched wires right 😆. But in all seriousness, 18 and 20 are very close in amp capacity.
 

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I just remeasured all... My results show the majority of wires at 20gauge with 1 or 2 wires on each side being 18 gauge. Most are 0.036inch conductors, with the larger being around 0.04.

I'm just going to leave it. Nothing says chopper like mismatched wires right 😆. But in all seriousness, 18 and 20 are very close in amp capacity.
It may not be the current capacity that is the issue. The resistance and capacitance per metre change with wire size. A larger conductor has a lower resistance than a smaller conductor. So a 10 gauge or 3mm sq wire has a lower resistance for a given length than a 12 gauge or 2.5mm sq wire. Some circuits are sensitive to resistance and performance drops with increasing resistance in series with the circuit. In automotive applications where we only start out with 12 volts the main concern is voltage drop, which increases with length. So to compensate for voltage drop you increase the size of the wire because what ever is connected in the circuit needs 12 volts and not 10.5 volts.

Ohm's law states that current flow is voltage divided by resistance and is given by Ohm's basic formula V=IR. So you can calculate the voltage drop by substituting in the equation. You can work out the voltage drop in the wire by measuring the resistance of the wire and using that for R. I is current and V is volts. Say you are switching a light on and the light is 24 Watts, then W divided by Volts (12) gives you 2 Amps (I) . Say we measure the resistance of the wire at 1 Ohm so that gives us I x R or 2 x 1 = 2v. So the voltage drop across or in that wire is 2 Volts. This gives you 10 Volts at the end of the wire rather than the 12 volts we started with.

After all that, now you know why the wires are different sizes even when the current through them is within the capacity of smaller wires.
 

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Wow! I appreciate that quite thorough answer... that probably took a really long time to type. You must be an engineer 😉. It makes perfect sense... If I had to guess, a lot of handlebar stuff is binary, and wouldn't carry a value based on voltage. I think it would be safe to say as long as all functions check out, then everything is happy in this case?
 

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Wow! I appreciate that quite thorough answer... that probably took a really long time to type. You must be an engineer 😉. It makes perfect sense... If I had to guess, a lot of handlebar stuff is binary, and wouldn't carry a value based on voltage. I think it would be safe to say as long as all functions check out, then everything is happy in this case?
Yes I am a electronics engineer, you guessed that right. Sorry to disappoint you but the Fury is not a digital device other than the ECU. The lights and switch gear are just plain old wires, resistors or load (headlamp and turn signals) and relays.

Take the headlight as an example, the switch to turn the headlamp on is tiny, there is no way it could carry the current to run the headlamp. So what you do is run a large wire from the battery to a relay and another large wire to the headlamp. You also run a smaller wire from the battery to the headlamp switch and from the headlamp switch to the relay. When you turn the headlamp on you are actually turning on one side of the relay, which in turn turns on the other side of the relay which goes to the headlamp. Now the low voltage, low current side of a relay needs a certain voltage to turn and stay on. If it needs a minimum of 12 V and it only gets 11 V it may or may not turn on and if it does turn on it may chatter and you will see the headlamp flickering. When you only have 12 V to start with you can't afford any loss, which comes back to my point in my last post. Engineers never use or specify something just for fun, it's not in our nature. We calculate it out, test where possible, measure and then add in an anti bugger factor. If it's a wire we will either use a size or two up or de rate the voltage and or current. Civil engineers regularly over spec beams in buildings knowing that builders often put smaller beams in to cut corners and make more profit. It's the anti bugger factor at work.
 

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It's the anti bugger factor at work.
Lol, we call that a factor of safety in my line. Last thing you want is snapped bolts, material failure, and a scrapped rocket engine!
 
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I can second that as a Civil Engineer & a Builder!
Lol, we call that a factor of safety in my line. Last thing you want is snapped bolts, material failure, and a scrapped rocket engine!
Technically it is a safety factor. In the faculty of engineering at the University of NSW it was always referred to as the anti bugger factor, mainly I think so that we would remember to make allowances for the things that go on in the real world. I remember well the senior professor of electronics engineering saying in a lecture that if someone can stuff up your design they will so plan for them to bugger it up. Over spec everything. LOL.

I've seen all manor of "changes" to things being built to "specification". In every case material was taken out or the wrong stuff was put in. Ever see a piece of machinery come off it's mounting because the contractor used mild steel bolts instead of high tensile bolts? I have and two people got badly injured. That was a messy scene, the facility owner decided that he did not want to pay an engineer to supervise the construction of the machine mounts. So he saved some money but lost the court case when the insurance company asked for an engineers certificate of compliance. The design engineer proved that the mounts were not constructed to the specification so liability went to the facility owner, but I digress.
 

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Seen a lot of bad things. Worked as an EMT for a couple of years in addition to how I make my money. Not for the faint of heart
 

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In addition to the excellent comments, part of up-sizing wire is resisting vibration induced embrittlement (it work-hardens and breaks if it's too thin to resist vibration).

Automotive wire is designed to resist heat, solvents, vibration, and provide a set of useful identification markings.

 

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Wow! I'm really impressed at what this old forum post dug up.. apparently we're all engineers here. Okay, you would all be proud of me... I pulled and redid all necessary wires to the appropriate Gauge (16, you all were right). Being an ME I tend to put less effort into the electrical side, so I appreciate the push toward the quality and reliability I'm looking for in this bike. It feels great knowing now that it's a job done right. I lost my pretty heat shrink ends, but the tape is almost unnoticeable.

On a side note, putting all wiring back into the headlight bucket has to be some sort of baptism into the fury world with how difficult it was lol.
 

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