Minimal 550 Bobber Schematic

[Normk]

Creating ones own wiring diagram and adding circuits as each is understood is an excellent means of increasing understanding.

I think it was in the 1970's when the Japanese bike makers moved from grounding components to the chassis. bodywork and adopted a common ground wire system. This has advantages in terms of assembly and in reducing corrosion issues with connections but, here's the rub, the ground circuit must use wire of sufficient gauge in order to avoid high voltage drop. Unfortunately this is usually not the case.

Most motorcycles have quite simple electrical systems (for the other side of that coin, look up an ST1100A Honda with ABS/TCS and review the wiring diagram. It isn't actually that bad once one studies the system) and the GS series is no exception.

These systems have the only significant electrical load in the headlight and related circuits so this load affects both insulated (positive or "supply side") and grounds. One can perform a very useful test by switching on high beam and measuring the voltage between the left hand (bike's left) headlight terminal and a good ground such as an engine bolt or battery negative. The voltage drop measured should be less than 1/2 volt, although it is common to see more than one volt.

Let's consider the implications: when the charging system is operating at full voltage, approximately 14.5 volts, the headlight should have 14.5 volts applied across the high beam to ground terminal. If we measure one volt between the ground terminal of the light and ground, that leaves only 13.5 volts across the bulb and so the light will be less than we hope. Adding another (14 guage) wire soldered to the ground terminal in the headlight plug and connected to a frame/chassis bolt will drop this loss to zero and we will see 14.5 volts to the headlight which is both obvious and good news.

Everyone will see that as obvious but what some fail to see is that the remainder of the components being grounded through the common ground wire will benefit equally. The ground wire will now have an additional ground path which will reduce loss for the other components which will also benefit because the headlight current will be mostly diverted from the common ground wire. This helps everything and is a simple 1/2 hour project which can be done anytime.

If someone does not know how to remove the ground connection from the headlight plug, reply on this thread and I can post a description and sample photo.

 

[gert du prez]

Hey, whatever 'more' information can be spread, the better.
So yes, please add some clarification (description, pictures,...)

thanks !

G

 

[Normk]

Here's a view of another headlight plug but most use a similar system to retain the terminals within the body of the plug.

One uses some sort of tool to press the retaining device back iin order to allow the terminal to be withdrawn from the plug body. Inspection combined with experience allows one to determine the direction from which the terminal needs to be withdrawn. Some terminals go out the "front" of the plug while most come out the "rear" or wire side. Some terminals have a tang as part of the terminal while others are retained by a tang which is part of the plastic plug body. Round terminals often have several tangs or a skirt which spreads. Again, inspection usually reveals the solution to removal.

In this case, I think I am only allowed one photo, the terminal was removed from the headlight plug and a second wire was soldered to the top of the terminal. The other end of the wire was crimped and soldered into an eye terminal which connects to a frame bolt as outline in my previous post.

Again, the reason for this was to add an additional ground circuit to the common ground. While it would have been beneficiail to disconnect the headlight from the common ground and to provide it with a heavier and shorter ground wire in order to reduce loss, it is even better to add the wire to the existing circuit. Adding the wire reduces voltage drop (loss) in both the headlight's and common ground circuits.

This is the last point but obviously the initial one for the decision to install the extra ground: a voltmeter placed between the headlight ground terminal in the headlight plug with headlight on high beam showed over one volt drop in the ground. Installing the extra ground makes the headlight brighter; it also reduces heat within the common ground circuit which just might have been concentrated at some "choke point".

 

[posplayr]

I have not done a wire size analysis for a while, but it appeared to me that most of the voltage drops were in the connections and switches mostly due to corrosion. Several people have gone to headlamp relay solutions to eliminate voltage drops in the original harness and headlamp switch controls.

Recall that all of the charging return current comes back to the R/R (-) terminal so you need to insure that there is a good connection between both the harness common ground (B/W) wire as well as to the frame to pickup the frame returns. Using a single point ground at I have described in the past is the best strategy. If you run a separate headlamp ground, it should be connected to the same place.

Some links to prior posts:

High Performance Power and Grounding

Ground Loops

​

 

[Normk]

There is no advantage to be gained by a single point ground or running a headlight ground wire back to the VRR ground point. It simply adds complexity and, unless the long ground wire is quite large gauge, increases voltage drop. The frame and engine are essentially a zero voltage drop under starting motor loads and even a lower loss issue for small loads such as headlight.

There are far too many messy bike wiring jobs created by running wires were the need not be. Just my $0.02. If you don't agree, let the voltage drop figures stand for themselves. One does not see automotive manufacturers running common ground wires back from the rear of an automobile for just this reason.

Common grounds on bikes are a production cost saving more than anything and are a reasonable approach for such small electical systems, given the proximity of components but they usually compromise too much by using tiny wire sizes.

I'm not trying to change anyone's mind but simply hoping to spare someone unneeded expense and problems.

 

[posplayr]

There is no advantage to be gained by a single point ground or running a headlight ground wire back to the VRR ground point. It simply adds complexity and, unless the long ground wire is quite large gauge, increases voltage drop. The frame and engine are essentially a zero voltage drop under starting motor loads and even a lower loss issue for small loads such as headlight.

There are far too many messy bike wiring jobs created by running wires were the need not be. Just my $0.02. If you don't agree, let the voltage drop figures stand for themselves. One does not see automotive manufacturers running common ground wires back from the rear of an automobile for just this reason.

Common grounds on bikes are a production cost saving more than anything and are a reasonable approach for such small electical systems, given the proximity of components but they usually compromise too much by using tiny wire sizes.

I'm not trying to change anyone's mind but simply hoping to spare someone unneeded expense and problems.

That is about the fastest "jump to a conclusion" I have ever seen. Sorry the links explain if although the pictures are all gone.

 

[Normk]

?

 

[mindtrip]

http://www.mtsac.edu/~cliff/storage/gs/550_Schematic.pdf

i do believe this is what we were looking for!

 

[kingstonphoto]

can anyone post pictures of their setup?

 

[Steve]

can anyone post pictures of their setup?

This thread started TWO YEARS AGO.

What "setup" are you looking for?

.

 

[kingstonphoto]

This thread started TWO YEARS AGO.

so??? id like to see the actual set ups rather than diagrams

 

[Pendulum]

so??? id like to see the actual set ups rather than diagrams

Are you on Canibeat? I doubt there's more than 1 Kingston Photo around...

I'll see if I've still got my drawings from my 550. What year do you have?

 

[kingstonphoto]

Yes I am. Not in that game anymore. I have a 77 gs550

 

[Pendulum]

Yes I am. Not in that game anymore. I have a 77 gs550

wrd, I've got a '79 so my schematics will be the same as your bike would need. PM me with exactly what you want to see/know.

 

[bobbed]

So what about no starter kick only do u need to run a different ingnition and does the rotor have to magnets rather then one dumb questions I know thanks

 

[posplayr]

Bump, I added the original powerpoint files to the first post.

 

[posplayr]

Bobber Bump

 

[blbiker56]

Hey Posplayr,

You seem to really know your stuff. I am in the middle of a project which is a 1980 gs550. I did use your wiring diagram, and it has been great and fairly easy to follow (being my first shot at electrical). I did have a question. I finally finished the harness last night and she almost started and was sputtering, and then nothing. I pulled the spark plug to check for spark and nothing. I went inside and had dinner, then went back outside and tested the spark plug again (didnt change anything) and it had spark! Now, it has no spark. I have been working on the bike for 2-3 hours trying to find why it is still not sparking. I have a cheap harbor freight multi meter and the coils read around 5.5 ohms. is this normal? also if I leave the ignition on the left side coil starts to get very hot.

Ok, now for my questions.

Is there a way to test my ignitor?
Will the Dyna S ignition work with this wiring diagram?

I really would appreciate any feedback.

Thanks,

 

[posplayr]

Is your ignitor a dyna S? It doesn't matter; there is a test procedure in the manual for testing an ignitor. Except if the problem is intermittent you test will pass when it is working and maybe fail when it is not.

One coil will always get hot if you leave the key on and that says that the side of the ignitor is at least turning on that Coil.

The negative side of the coils will be pulled low when the ignitor is allowing current to flow through teh coil. It only does one coil at a time.

There should be nothing keeping you from installing the Dyna S into your harness.

 

[blbiker56]

OK, Finally got my Dyna DS3-2 in today! it comes with a wiring diagram, so if all goes well, ill post how I wired up to this minimal wiring setup. Ill keep y'all updated on the electrical build.

Also, has anyone used these Dyna s modules? Does it get rid on the "Ignitor" box?

Thanks.