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SH 775 install

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I am installing a a sh775 on my 78 750. It's one with only one fuse. Do I want to eliminate the leg going through the lights? If so what do I do with the green and white wire that goes to the light and the red and white one coming back? I usually can find the answers by reading old post but I am still not sure. Money is tight and I dont want to screw this up. Any advice would be appreciated, thank you.
 
Ignore that leg to the light bucket and go direct to the r/r with all three stator wires. If you take the output + of the r/r to the 'tee' in the harness you should be ok. If you take the output to the battery positive ( I wouldn't) you will need an extra in-line fuse
 
Not only do you have just one fuse, you also have separate rectifier and regulator. Think of them as one package. Take the three wires coming from the stator, wire them directly to the three inputs of your SH775. The white/green and white/red wires that go to the headlight switch can simply be ingnored. Once they are disconnected, you can tuck them away anywhere you want. There will be no power on them at any time, so there is no great need to insulate them, but I tend to wrap some tape over them so they don't confuse anyone down the line.
 
Now would be a good time to get a single point ground organised if you haven't already.
I have collected the two harness return b/w wires, the r/r negative and the starter solenoid ground together at one of the solenoid mounting screws. There is then a short wire from there to the battery negative. It's a very low cost mod that will make life a lot less confusing for the new r/r. Find Posplayr's sig or search SPG
 
mainiac said:
I am installing a a sh775 on my 78 750. It's one with only one fuse. Do I want to eliminate the leg going through the lights? If so what do I do with the green and white wire that goes to the light and the red and white one coming back? I usually can find the answers by reading old post but I am still not sure. Money is tight and I dont want to screw this up. Any advice would be appreciated, thank you.
Click to expand...

Brendan W is correct. I am going through this myself on an 82 1100E and just finished my homework. Look at these threads from posplayr for the details:

http://www.thegsresources.com/_foru...-Charging-System-Health&p=1138531#post1138531

http://www.thegsresources.com/_forum/showthread.php?139115-Ground-Loops

In the wiring diagram shown in the first link it shows two positive leads and two negative leads from the R/R. Your SH775 only has one each, so just treat the two as one on the wiring diagram. I will be capping the unused wires in my harness just to minimize confusion in the future, as mentioned.


Mark
 
Brendan W said:
Now would be a good time to get a single point ground organised if you haven't already.
I have collected the two harness return b/w wires, the r/r negative and the starter solenoid ground together at one of the solenoid mounting screws. There is then a short wire from there to the battery negative. It's a very low cost mod that will make life a lot less confusing for the new r/r. Find Posplayr's sig or search SPG
Click to expand...

I don't see the point in gathering together the various b/w ground wires and physically attaching them together. The frame is in of itself a common ground. Just make sure all the b/w wires have clean contact to the frame or battery and you are fine.
 
Nessism said:
I don't see the point in gathering together the various b/w ground wires and physically attaching them together. The frame is in of itself a common ground. Just make sure all the b/w wires have clean contact to the frame or battery and you are fine.
Click to expand...

In my limited understanding of these things the r/r drives the bike. There is a top voltage 14V and the bottom 0 V. If you introduce the frame into the return there will be some resistance between the harness return and the r/r negative, let's say 0.1 Volt drop at normal operating load. Now the headlight only sees 13.9 V.
The same applies to the battery if the returning currents come back to the battery negative. The r/r is not seeing the battery voltage and the charging rate will be lowered as a consequence for the same reason that the headlight bulb is putting out less light.
 
Nessism said:
I don't see the point in gathering together the various b/w ground wires and physically attaching them together. The frame is in of itself a common ground. Just make sure all the b/w wires have clean contact to the frame or battery and you are fine.
Click to expand...
Because frame is not the lowest voltage point in the system.

of course if you polish your grounds everyday with sandpaper you will be fine
 
Brendan W said:
In my limited understanding of these things the r/r drives the bike. There is a top voltage 14V and the bottom 0 V. If you introduce the frame into the return there will be some resistance between the harness return and the r/r negative, let's say 0.1 Volt drop at normal operating load. Now the headlight only sees 13.9 V.
The same applies to the battery if the returning currents come back to the battery negative. The r/r is not seeing the battery voltage and the charging rate will be lowered as a consequence for the same reason that the headlight bulb is putting out less light.
Click to expand...
That is exactly right. By colic sting the grounds you only have one place to be of concern for ground returns to the R/r(-). Keeping the battery wire seperate keeps the voltage drop between battery and 4r/r(-) only a function of the charging currents and not the entire current supplied by the alternator.
 
The frame is a perfectly acceptable grounding point for the system. That's why virtually every motorcycle and automobile ever built uses the chassis/frame as the ground path.
 
Nessism said:
The frame is a perfectly acceptable grounding point for the system. That's why virtually every motorcycle and automobile ever built uses the chassis/frame as the ground path.
Click to expand...
Yet another universal law of gwizzickx based on an analysis of similarity.
 
Every bike and car I ever had used the frame and or chassis as a return. I never faulted any of them. The GS is different. The electrical system is coming to end of life and there is the opportunity to do it better second time around. Yes the benefits may be marginal but why not shoot for the top. If for no other reason than to have all the return connections in plain sight the SPG is a good idea. Better than wondering what is happening on top of the airbox or under the battery.
 
Brendan W said:
Every bike and car I ever had used the frame and or chassis as a return.
Click to expand...

To keep this discussion more focused, on the typical GS, (Other that starter return currents) what currents run through the frame by design or otherwise?
 
posplayr said:
To keep this discussion more focused, on the typical GS, (Other that starter return currents) what currents run through the frame by design or otherwise?
Click to expand...
Leaving out the intermittent oil pressure, starter relay coil etc........
Frame returns
Lights
Ignitor
Coil primary
Fuel gauge

Gear indicator and coil secondaries probably have a choice and maybe split between the starter return cable and the engine mounts ?
 
Steel has a conductivity of 3-15% compared to copper at 100% and aluminum at 61%, Nearly all automobiles and motorcycles have used the frames because it was convenient and cheep until computerized controls came along. I ran separate grounds to the archaic computer in my '85 Supra and it made a world of difference compared to the body parts it was bolted to. Add in steel and aluminum bolted together and the frame ground becomes worse with time. Frames suck for grounds, there is no other way to put it.
 
OldVet66 said:
Frames suck for grounds, there is no other way to put it.
Click to expand...

Unless it's an aluminum frame.;)

Actually not sure where you get any type of a 100% number on copper since conductivity is usually measured in units of Siemens/Meter. That would make copper a superconductor. If your 100% scenario for copper had any meaning, then silver would be like 120%. Just nitpicking. Agreed that frames don't make a good source for conducting grounds.

Here are the actual numbers in units of 10.E6 S/M:

Silver: 62.1
Copper: 58.5
Alluminum: 36.9
Iron: 10.1
Carbon Steel: 5.9
 
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It was a comparative chart, silver rating 105 (I suppose copper was 100% as a standard) but it shows just how bad steel frame grounds are in comparison.
 
Like I said, I'm just nitpicking. It's an occupational thing... Spent 25 years as a test engineer.;)
 
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