Wire gauge?

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What wire gauge is needed from the battery to the starter solenoid. Was this a factory wire (with a loose plastic jacket)?

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I don’t like it because the braided jacket is a conductor, waiting to short out against something. Nice thing is it’s super flexible. Agree it could be an audio power supply cable. I can put a couple of layers of good quality loom if I decide to repurpose it.
I searched current draw for the starter and the spec is 75A @ 300 rpm engine speed. Looking at wiring specs, this call for some huge a$$ wire size.
Other posts here recommend 6 gauge and that’s what my Frankenwire looks like. I don’t have any 6 gauge in my stash but have a nice 8 gauge power cable (factory fused at 60A). If I use the 8 gauge am I headed for trouble?
I can buy 6 gauge welding cable (usually quite flexible) if that gauge is really necessary.

Opinions?
 
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I don’t like it because the braided jacket is a conductor, waiting to short out against something. Nice thing is it’s super flexible. Agree it could be an audio power supply cable. I can put a couple of layers of good quality loom if I decide to repurpose it.
I searched current draw for the starter and the spec is 75A @ 300 rpm engine speed. Looking at wiring specs, this call for some huge a$$ wire size.
Other posts here recommend 6 gauge and that’s what my Frankenwire looks like. I don’t have any 6 gauge in my stash but have a nice 8 gauge power cable (factory fused at 60A). If I use the 8 gauge am I headed for trouble?
I can buy 6 gauge welding cable (usually quite flexible) if that gauge is really necessary.

Opinions?
Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.

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Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.

I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops at curve #3 (intermittent duty). On the left we see it's valid for about 5-6 ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.


Starter Wire Size..png
 
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Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.

View attachment 343296

Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.

I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops. On the left we see it's valid for about 11ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.


View attachment 343297
This is great info Jim, thanks! With this new to me intel, I think I’ll remove the wire I put back in and reinstall a new one since I have nice 8 gauge wire in stock.
I found the 75A current draw in another thread in this group.
 
Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.

View attachment 343296

Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.

I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops at curve #3 (intermittent duty). On the left we see it's valid for about 5-6 ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.


View attachment 343297
got one of those that's not all marked up?
for reference and maybe shop wall use. ;^)
 
Your source for current draw is wrong. Hitachi specs our starter at half a KW . So, 500W div by 12V gives us a little less than a 42A draw.

View attachment 343296

Automotive (motorcycle) engineers tend to overbuild electrical systems. No idea why, but they do.
For determining wire size, I use the chart in AC-43.13. It's the aircraft mechanics 'bible'. Was written by the FAA based on what aircraft makers use. It's accurate, dead simple and what I used for over 40yrs.

I graphed out the starter needs below.
Purple on left denotes 12V.
Purple on right denotes 50A (to add a margin to the 42A we use).
Chase the 50A down (red line) until it stops at curve #3 (intermittent duty). On the left we see it's valid for about 5-6 ft of wire. Where those two lines intersect is our required wire size. When you're past one size, you automatically select the next bigger gauge.
That would be 10ga wire.... which is what my SG has run for the last 6-8 yrs with absolutely no problems.


View attachment 343297
I was taught to go by the NEC they know a little something about electricity and conductors.
Based on what they say and what I learned in 45 years of working with automotive and industrial electricity I use 6ga works very well for me.
I'm not saying 10ga can't work but 6ga is better. Wire size is one thing where bigger is usually better.
1738183500222.png
 
got one of those that's not all marked up?
for reference and maybe shop wall use. ;^)
Keep in mind, Gary, this chart assumes you're using wire spec'd for aviation.... best quality in other words. If you use this chart, always round up to the next larger gauge to add a cushion.


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I was taught to go by the NEC they know a little something about electricity and conductors.
Based on what they say and what I learned in 45 years of working with automotive and industrial electricity I use 6ga works very well for me.
I'm not saying 10ga can't work but 6ga is better. Wire size is one thing where bigger is usually better.
One major factor left out in your chart is the length of the wire.... that's factored into the AC-43.13 chart. To stay below a 1 volt drop, we need to know the length. For instance, if you plot below the curve, all the way down to 2 ft of wire length, a 14ga wire would still keep you at or below the 1v drop. No one in their right mind would use 14ga to the starter solenoid, but at less than 2ft, you could.

Shortly after I got the SG running, a buddy questioned the wisdom of 10ga wire. As a test, we disconnected the TCI box and spun the starter until we got a noticeable drop in volts/rev's... about 30-45 sec continuous iirc. The wire to the solenoid never got warm to the touch. I've got videos on Youtube of starting the bike. It spins fast and lights off almost immediately. It works just fine with 10ga.

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I believe it's for 75 feet or less. Also it's for temp of wire and type of insulation.
As you said yours is based on using wire spec'd for aviation.
GM, Ford, Honda, Yamaha and all the other manufactures don't like to waste money. There has to be a reason they "overbuild electrical systems".
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