79 GS750 wiring no battery

[Guest]

got a gs750 project and need another perspective to get spark, thanks in advance for any help you can give me

the bike came with no starter and a demo'd wiring harness. I decided to make a wiring harness from scratch with no battery. I have a stock stator and rectifier. the coils, ignition, and points are from dyna. I have an spst switch for the brights, and another for all the rest of the lighting to cut off power to everything other than the ignition while i am kicking it over. I'm using 1 10a fuse for the ignition, and another for all the lighting. I'm also using a capacitor, and LED lights so they won't be quite so dim at low rpm's.

I have a schematic I drew up and attached it to show you what all the wiring looks like. Hoping someone knows a bit about these bikes and can let me know what could be causing a problem in getting spark if it is identical wiring to the schematic.

tested the coils (6ohm ea), regulator (1-4.5 v), stator(but only one of the three wires and it was giving out 2.35 v), and lastly i tested the points, but was having trouble getting more than a momentary ohm reading.

I'm noticing nothing coming from the capacitor, but after kicking it like a tweaking mule i was getting 5-6.5 volts from the capacitor to the ground, but after leaving it be for 10 minutes it went back to putting out nothing. I had the ignition hotwired during and after doing this, so i'm not sure if that would drain the capacitor when it has a full circuit, or if it would do this regardless. tomorrow i'm going to test each stator wire, and make sure there all evenly putting out volts.

past the stator potentially being an issue, or the hotwiring potentially being a problem for the capacitor, do you guys see any potential issues with the wiring? are my numbers sounding reasonable? should I just get a battery and stop being stubborn about running it without one?

[Brendan W]

Sorry can't read the wiring diagram.
I think you cannot rely on a capacitor to have enough charge to do meaningful tests. Get a battery. They weren't called accumulators for nothing.
To check the stator output the bike needs to be running with the stator disconnected and the battery is what keeps the ign supplied while you do checks. Stator output between any two should be near 80 Volts AC at 5000 rpm
When everything is sorted you can always ditch the battery at that point.

[switchback_bomber]

When everything is sorted you can always ditch the battery at that point.

theres a thought! although im also partially just trying to save some money, so i might just keep it if I get one. I would still like to avoid getting a starter motor if I can, from what I've seen this shouldn't be an issue, what do you think? it seems like I can just put the battery + where I have the capacitor (after the regulator and before the key switch), and add a ground on the negative side.

I tried to upload the schematic again, but can't upload it any larger than the first, is there someway to upload that any larger? if not would you be comfortable pm'ing me your email so I can send you the schematic? i am fairly confident it should work, but a second opinion from someone more knowledgable than myself would be greatly appreciated.

thanks a bunch Brendan

[Brendan W]

Is there a capacitor is series with the key on the top right of the schematic?
DC will not go through a capacitor.
What I know about running bikes without a battery could be written on a matchbox but that capacitor looks all wrong.
It should be in parallel with the rest of the system in the same way that a battery would be.
A battery is amongst other things a capacitor. I smooths the regulator output as well as storing charge.

Have a look in our library for ideas about educed harnesses, testing and links to other harness ideas

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A09

[switchback_bomber]

Also curious if the grounds are better on the motor than the frame, or are they both equally adequate? is 1 10a fuse is enough for all the lighting? I know 1 10a fuse was what the factory ignition system had, but is 1 10a what I would need for the Dyna ignition setup(potentially a question for dyna)? is the capacitor relatively pointless with the battery, or could it still be beneficial in the circuit? lastly when i was working on wiring the points, i noticed a wire (the black from electronic ignition to the points i believe) looked pretty oxidized/fried, and did not want to take any solder, is this a wire I can replace? is this a sign of a problem with something in the ignition?

[Brendan W]

Nominally a 10A fuse will handle 120 Watts. For a standard headlight and tail etc this should be ok.
However you have LED lighting which reduces the load.
Now you may have another problem.
The stock charging set up relied to an extent on lighting load to take some of the output. Now that is not being used you have more pressure on the system to find places to dump the excess and you don't even have a battery to help out. A solution for this excess problem is to replace the stock shunt regulator with a series regulator. This is what I and many others have done even with a battery to protect the stators.
Fried wires are easy to replace. The question is why did it fry on such a low current part of the harness.
And yes, a capacitor is pretty pointless with a battery installed.

[switchback_bomber]

I have the wiring as stator>regulator>spst key switch > capacitor> fuse box>ignition wire, master lights switch, and brights switch

the lights are pretty straight forward, but the ignition wire i have going to the coils and the electronic ignition, the negative side of the 1-4 coil goes to the tach and the electronic ignition, and the negative side of the 2-3 coil just goes to the electronic ignition. from the electronic ignition i have a ground and a red wire, a black wire, and a white wire going to the points.

Now that you mention that i looked at some schematics again, and the capacitors clearly are grounded, for some reason I hadn't noticed this, and thought they ran in series (probably because thats how electric guitars capacitors are wired). just had one of those ah-ha moments followed by feeling a little dumb for not picking up on that earlier... I guess thats why i'm here though

Thanks for your help Brendan, I am so thankful to be able to take on these projects during a time where the technology exists to be able to get help from people all over the world, and even more grateful that people such as yourself exist to help others, out of nothing more than passion and a desire to pass on their knowledge

[switchback_bomber]

My guess as to what happened to fry the wire was very poor wiring but this might just be wishful thinking. the bike has been owned by three people before me who thought themselves to be a bit more handy than reality. the carbs were disassembled, but they never reassembled them or even bothered to buy a rebuild kit, the seat was replaced with a hideous fiberglass monstrosity with the cushion bolted on (talk about a pain in the a**), and the wiring harness looked like freddy kruger got inside a bikers dream and tortured him by working on his bike

[Brendan W]

I think you're about ready for this

https://www.thegsresources.com/_forum/showthread.php?171846-Top-10-Newbie-Mistakes

Measure twice cut once is as true for old bikes with unknown history as anything else and you will save a lot of time and money in the long run by going at a project methodically. There is no end of helpful and better informed people on here who will lend a hand in a heartbeat to any one who wants to do it right.
This is our library, complied and uploaded fro the benefit of anyone prepared to read and learn.

http://members.dslextreme.com/users/bikecliff/

[switchback_bomber]

At the risk of sounding like I just want someone to tell me what to do, and avoid researching anything, I'm hitting alot of dead ends in figuring out the wiring. I have heard people tell me the stator is electromagnetic and needs a battery, I have seen diagrams with more or less wires coming from stator, regulator, ignition, or points than I have on my equipment, i have seen diagrams with no electronic ignition, and the list goes on... I have searched endlessly for a diagram that reflects what i need and is credible with no luck. I simply need someone to look at my diagram and tell me whats right or wrong. All I am trying to do is get a spark, but I need to know my wiring is good even if it is only theoretically. the stock wiring diagram would be very helpful IF i didn't have Dyna ignition

[Steve]

..., the stock wiring diagram would be very helpful IF i didn't have Dyna ignition

The Dyna ignition changes very little, in regards to the wiring.

In the stock wiring, power goes to both coils, then a wire from each coil goes to one of the two sets of points, then to ground. With the Dyna setup, power goes to both coils, then a wire from each coil goes to the Dyna module, which is then grounded. The only real difference is that the Dyna module also requires a power wire.

I looked at your diagram (as requested), but had a hard time reading it. From your description of power flow, "stator>regulator>spst key switch > capacitor> fuse box>ignition wire, master lights switch, and brights switch", I have to question the capacitor. What are the values and how is it wired? References to electric guitars mean nothing to me, I have never dealt with them.

On the ignition side, you mention your electronic ignition module you say you have a white wire going to the points. If you have installed electronic ignition, you should not have any points.

Finally, I will have to ask the same question I have asked many others that have tried to go this route: what is your motivation to ditch the battery?

.

[Brendan W]

I have heard people tell me the stator is electromagnetic and needs a battery

These machines have permanent magnet generators. You spin the magnets inside coils of wire and that creates a voltage.
Alternators in more modern machines have an electromagnet or field coil instead of permanent magnets. That needs current to make the magnetic field and for that you generally use a battery although there are such things as self exciting alternators but we're going way off track here.
Points are switches. They switch off the flow of current through the ignition coils which causes a spark. The problem is that they wear because they have sparks each time the open. Fully electronic ignition replaces the points with contactless switches or pickups..
Are there points still on the bike and is the Dyna unit even wired in?
Here are some typical Dyna wiring diagrams

http://housewiringdiagrams.me/design/elegant-of-dyna-2000-ignition-wiring-diagram-fresh-instructions-concept-current-5723

The points are replaced by the triggers.
Looking at your wiring diagram it looks like it could work with the capacitor taken out of there. I can't make out the two modules below the coils but if they are wired up right it should go. It's one thing to get it working but another for it to be ok for service on a running bike so for me the stock wiring layout is the go to arrangement.

[switchback_bomber]

Attached updated wiring and cropped out all the lighting, so hopefully it is legible. where diagram says Capacitor i will likely end up having a battery

Brendan; I get how the stator works, i was just giving examples of things i am seeing and being told that I(as limited as my knowledge is) know are wrong, with all the misinformation having something in my wiring be wrong is a good possibility. I'm honestly not sure whether or not the points are still there since the stuff was already on the bike when I got it, but it has the thin wires coming from it and a grey sleeve that I don't believe would have come from suzuki. the dyna ignition is old, and the regulator is factory. the fact that someone was having serious problems with the electronics, enough to tear the wiring apart, coupled with the fried wire i came across, i'm thinking the regulator is bad, and if it is bad enough to fry that wire, it likely damaged the dyna III ignition module.

I'm going to call dyna and double check, but the Dyna s CDI seems like an awesome solution. if I understand it correctly, I can pull out whatever is in the spot where the points were, install it, pitch whatever was there before, along with the ignition module, and attach it to power and the coils. I'm also definitely getting a new regulator, looking at getting a rick's, or if you have any recommendations for a good series regulator I'm certainly not set on a Rick's. The coils I know are good at 3.4 & 3.5 ohm, and if aesthetics mean anything the stator seems fine (still haven't gotten around to testing the other 2 wires).

Steve; When I wrote that Brendan had just told me that the capacitor is not meant to be run in series which he is 100% correct, the wiring i was explaining was just what was in the photo(even though it was wrong). in guitars wiring capacitors are run in series... pretty much just thinking out-loud as to where i got the idea the capacitor was meant to be run in series.

My desire to run without the battery came from the fact the bike came with no starter and no battery, wanted to save some money by not getting either, + I'm stubborn as hell, and maybe a little romanticized thoughts of a bare bones cafe racer. Still thinking i'll leave the starter out, but I am pretty well giving up on the no battery concept

[Brendan W]

I'm seeing guys on here picking up used Sh775 series regulators
on ebay for about $50

[switchback_bomber]

i'm not seeing anything used at the moment. there are new ones from china at $20, or US stock for $50. my one concern is they are all just generic, but with good reviews. are you just running a generic? Is the black port + & -, and grey port going to the stator wires?